[AWS] Remove duplicate fields from agent.yml and use ecs.yml for ECS fields

[kaiyan-sheng]

What does this PR do?

Similar to #4567, this PR is to remove all duplicate fields from agent.yml files from all data streams under AWS package and use ecs.yml file to document all ECS fields to avoid re-defining these fields again.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.

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Build stats

• Start Time: 2022-11-15T22:34:53.830+0000

• Duration: 34 min 21 sec

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Test	Results
Failed	0
Passed	162
Skipped	2
Total	164

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (13/13)	💚
Files	92.857% (13/14)	👎 -4.829
Classes	92.857% (13/14)	👎 -4.829
Methods	84.232% (203/241)	👎 -7.037
Lines	95.697% (5204/5438)	👍 3.992
Conditionals	100.0% (0/0)	💚

[zmoog]

The .md files in docs mostly have a few description changes, but it's probably due to the switch to the ECS field definitions.

LGTM.

[kaiyan-sheng]

@zmoog Yep exactly :) Thanks!