fix(pipelines): ensure assets with same hash but different destinations are published separately (#34790)

### Issue

Closes #31070

### Reason for this change

Assets are missing to be published in CDK pipelines when stacks with different synthesizers are used for the same account and region. When assets have identical content hashes but need to be published to different destinations (different publishing role ARNs), they were being incorrectly grouped together, causing assets to only be published to one destination instead of all required destinations.

### Description of changes

• Modified publishAsset() method in packages/aws-cdk-lib/pipelines/lib/helpers-internal/pipeline-graph.ts
• Changed asset tracking key from using only stackAsset.assetId to a composite key: 
`${stackAsset.assetId}:${stackAsset.assetPublishingRoleArn || 'default'}`
• This ensures assets with the same content hash, but different destinations are treated as separate publishing jobs

### Describe any new or updated permissions being added
NA

### Description of how you validated changes

Checked with the code in #31070 and made sure there are 2 asset stages, locally ran the asset commands and verified that they are being deployed to right buckets:
```
muralikl@b0be83688a18 cdk.out % cdk-assets --path "assembly-pipeline-asset-stack-Staging/pipelineassetstackStagingdevlambdastackEC748226.assets.json" --verbose publish "a26bd817a0dac44954b5caf83f5880a96f831e43b56157224e073b49f236eb4e:current_account-us-east-1"                   
verbose: Loaded manifest from assembly-pipeline-asset-stack-Staging/pipelineassetstackStagingdevlambdastackEC748226.assets.json: 2 assets found
verbose: Applied selection: 1 assets selected.
info   : [0%] start: Publishing LambdaFN/Code (current_account-us-east-1)
verbose: [0%] check: Check s3://cdk-dev-assets-123456789012-us-east-1/a26bd817a0dac44954b5caf83f5880a96f831e43b56157224e073b49f236eb4e.zip
verbose: [0%] build: Zip /Users/muralikl/Downloads/aws-cdk/packages/@aws-cdk-testing/framework-integ/cdk.out/asset.a26bd817a0dac44954b5caf83f5880a96f831e43b56157224e073b49f236eb4e -> assembly-pipeline-asset-stack-Staging/.cache/a26bd817a0dac44954b5caf83f5880a96f831e43b56157224e073b49f236eb4e.zip
verbose: [0%] upload: Upload s3://cdk-dev-assets-123456789012-us-east-1/a26bd817a0dac44954b5caf83f5880a96f831e43b56157224e073b49f236eb4e.zip
info   : [100%] success: Published LambdaFN/Code (current_account-us-east-1)

muralikl@b0be83688a18 cdk.out % cdk-assets --path "assembly-pipeline-asset-stack-Production/pipelineassetstackProductionprdlambdastack4E5ABBC0.assets.json" --verbose publish "a26bd817a0dac44954b5caf83f5880a96f831e43b56157224e073b49f236eb4e:current_account-us-west-2"
verbose: Loaded manifest from assembly-pipeline-asset-stack-Production/pipelineassetstackProductionprdlambdastack4E5ABBC0.assets.json: 2 assets found
verbose: Applied selection: 1 assets selected.
info   : [0%] start: Publishing LambdaFN/Code (current_account-us-west-2)
verbose: [0%] check: Check s3://cdk-hnb659fds-assets-123456789012-us-west-2/a26bd817a0dac44954b5caf83f5880a96f831e43b56157224e073b49f236eb4e.zip
verbose: [0%] build: Zip /Users/muralikl/Downloads/aws-cdk/packages/@aws-cdk-testing/framework-integ/cdk.out/asset.a26bd817a0dac44954b5caf83f5880a96f831e43b56157224e073b49f236eb4e -> assembly-pipeline-asset-stack-Production/.cache/a26bd817a0dac44954b5caf83f5880a96f831e43b56157224e073b49f236eb4e.zip
verbose: [0%] upload: Upload s3://cdk-hnb659fds-assets-123456789012-us-west-2/a26bd817a0dac44954b5caf83f5880a96f831e43b56157224e073b49f236eb4e.zip
info   : [100%] success: Published LambdaFN/Code (current_account-us-west-2)
```

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: mrlikl

packages/@aws-cdk-testing/framework-integ/test/pipelines/test/integ.newpipeline-with-file-system-locations.js.snapshot/PipelinesFileSystemLocations.assets.json

@@ -1768,7 +1768,7 @@
      ]
     },
     "Source": {
-     "BuildSpec": "{\n  \"version\": \"0.2\",\n  \"phases\": {\n    \"install\": {\n      \"commands\": [\n        \"npm install -g cdk-assets@latest\"\n      ]\n    },\n    \"build\": {\n      \"commands\": [\n        \"cdk-assets --path \\\"assembly-PipelinesFileSystemLocations-Beta/PipelinesFileSystemLocationsBetaStack18199ECAE.assets.json\\\" --verbose publish \\\"8289faf53c7da377bb2b90615999171adef5e1d8f6b88810e5fef75e6ca09ba5:current_account-current_region\\\"\"\n      ]\n    }\n  }\n}",
+     "BuildSpec": "{\n  \"version\": \"0.2\",\n  \"phases\": {\n    \"install\": {\n      \"commands\": [\n        \"npm install -g cdk-assets@latest\"\n      ]\n    },\n    \"build\": {\n      \"commands\": [\n        \"cdk-assets --path \\\"assembly-PipelinesFileSystemLocations-Beta/PipelinesFileSystemLocationsBetaStack18199ECAE.assets.json\\\" --verbose publish \\\"8289faf53c7da377bb2b90615999171adef5e1d8f6b88810e5fef75e6ca09ba5:current_account-current_region-3d50c90e\\\"\"\n      ]\n    }\n  }\n}",
      "Type": "CODEPIPELINE"
     },
     "VpcConfig": {

packages/@aws-cdk-testing/framework-integ/test/pipelines/test/integ.newpipeline-with-file-system-locations.js.snapshot/PipelinesFileSystemLocations.template.json

@@ -1973,7 +1973,7 @@
      ]
     },
     "Source": {
-     "BuildSpec": "{\n  \"version\": \"0.2\",\n  \"phases\": {\n    \"install\": {\n      \"commands\": [\n        \"npm install -g cdk-assets@latest\"\n      ]\n    },\n    \"build\": {\n      \"commands\": [\n        \"cdk-assets --path \\\"assembly-PipelineStack-Beta/PipelineStackBetaStack1E6541489.assets.json\\\" --verbose publish \\\"8289faf53c7da377bb2b90615999171adef5e1d8f6b88810e5fef75e6ca09ba5:current_account-current_region\\\"\"\n      ]\n    }\n  }\n}",
+     "BuildSpec": "{\n  \"version\": \"0.2\",\n  \"phases\": {\n    \"install\": {\n      \"commands\": [\n        \"npm install -g cdk-assets@latest\"\n      ]\n    },\n    \"build\": {\n      \"commands\": [\n        \"cdk-assets --path \\\"assembly-PipelineStack-Beta/PipelineStackBetaStack1E6541489.assets.json\\\" --verbose publish \\\"8289faf53c7da377bb2b90615999171adef5e1d8f6b88810e5fef75e6ca09ba5:current_account-current_region-3d50c90e\\\"\"\n      ]\n    }\n  }\n}",
      "Type": "CODEPIPELINE"
     },
     "VpcConfig": {
@@ -2072,7 +2072,7 @@
      ]
     },
     "Source": {
-     "BuildSpec": "{\n  \"version\": \"0.2\",\n  \"phases\": {\n    \"install\": {\n      \"commands\": [\n        \"npm install -g cdk-assets@latest\"\n      ]\n    },\n    \"build\": {\n      \"commands\": [\n        \"cdk-assets --path \\\"assembly-PipelineStack-Beta/PipelineStackBetaStack1E6541489.assets.json\\\" --verbose publish \\\"ac76997971c3f6ddf37120660003f1ced72b4fc58c498dfd99c78fa77e721e0e:current_account-current_region\\\"\"\n      ]\n    }\n  }\n}",
+     "BuildSpec": "{\n  \"version\": \"0.2\",\n  \"phases\": {\n    \"install\": {\n      \"commands\": [\n        \"npm install -g cdk-assets@latest\"\n      ]\n    },\n    \"build\": {\n      \"commands\": [\n        \"cdk-assets --path \\\"assembly-PipelineStack-Beta/PipelineStackBetaStack1E6541489.assets.json\\\" --verbose publish \\\"ac76997971c3f6ddf37120660003f1ced72b4fc58c498dfd99c78fa77e721e0e:current_account-current_region-8b0ef02d\\\"\"\n      ]\n    }\n  }\n}",
      "Type": "CODEPIPELINE"
     },
     "VpcConfig": {