chore(java): use production staging bucket (#598)

This PR was generated using Autosynth. 🌈

Synth log will be available here:
https://source.cloud.google.com/results/invocations/3f419455-37e4-465d-8dc9-81639f5c110a/targets

- [ ] To automatically regenerate this PR, check this box.

Source-Link: googleapis/synthtool@c7824ea

Author: yoshi-automation

.kokoro/release/publish_javadoc.cfg

@@ -9,7 +9,7 @@ env_vars: {
 
 env_vars: {
   key: "STAGING_BUCKET_V2"
-  value: "docs-staging-v2-staging"
+  value: "docs-staging-v2"
   # Production will be at: docs-staging-v2
 }
 

synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-storage.git",
-        "sha": "1c330a9a5d8b1035a8b4979e8a8a587185d44c59"
+        "sha": "b39a67551866fb8e09755e4918f30f92754ab297"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "b19b401571e77192f8dd38eab5fb2300a0de9324"
+        "sha": "c7824ea48ff6d4d42dfae0849aec8a85acd90bd9"
       }
     }
   ],