Migrate STS from Arn to RuleArn, remove S3EndpointAuthSchemeStrategyFactory, and delete old rule engine tests

[S-Saranya1]

Motivation and Context

As part of enabling compiled endpoint rules for all services, the old interpreted endpoint rules path is being removed. This PR cleans up service-level source code that depended on the interpreted runtime — specifically in STS, S3, and related test modules.

This is one of 3 cleanup PRs (merging to a feature branch, released together):

• Config cleanup PR (#7268): Removes enableGenerateCompiledEndpointRules entries from all service customization.config files
• Codegen cleanup PR (#7269): Removes the flag from codegen, deletes the old interpreted code path, merges rules2 package into rules
• This PR: Migrates STS/S3 source code off deprecated internal classes and removes old rule engine tests

Modifications

• StsGetFederationTokenCredentialsProvider.java — Migrated from Arn (being removed with the old runtime) to RuleArn (available in the compiled path) for ARN account ID extraction
• StsAuthUtils.java — Same migration from Arn to RuleArn
• StsCredentialsProviderTestBase.java — Removed unused Arn import
• S3EndpointAuthSchemeStrategyFactory.java — Deleted. This runtime factory parsed auth scheme properties for the interpreted endpoint provider. The compiled provider handles auth schemes
  inline in generated code, making this class unnecessary.
• KnownS3ExpressEndpointProperty.java — Removed AuthSchemesProperty and BackendProperty inner classes that used the deleted auth scheme strategy. Only the BACKEND constant remains (still
  used by other S3 code).
• NamingConventionWithSuppressionTest.java — Removed reference to deleted S3EndpointAuthSchemeStrategyFactory from the naming convention suppression list
• S3CrossRegionSyncClientTest.java — Removed unused Mock import
• Deleted 11 old rule engine test files — RestJsonEndpointProvidersEndpointProviderTest, DefaultVisitor, RuleEngineTest, etc. These tested the interpreted rule engine's visitor interfaces
  and runtime classes that are no longer generated by the compiled path.

Testing

Make sure all the existing tests pass

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
• I have added a changelog entry. Adding a new entry must be accomplished by running the scripts/new-change script and following the instructions. Commit the new file created by the script in .changes/next-release with your changes.
• My change is to implement 1.11 parity feature and I have updated LaunchChangelog

License

• I confirm that this pull request can be released under the Apache 2 license

[github-actions]

This pull request has been closed and the conversation has been locked. Comments on closed PRs are hard for our team to see. If you need more assistance, please open a new issue that references this one.