Update codegen fixture files and fix tests

[S-Saranya1]

Motivation and Context

The core interceptors to pipeline migration moves auth scheme resolution and endpoint resolution from generated interceptors to dedicated pipeline stages. This changes the generated code, the AuthSchemeInterceptor and EndpointResolverInterceptor are no longer generated with resolution logic (it now lives in AuthSchemeResolutionStage and EndpointResolutionStage).

This PR updates the codegen test fixture files to match the new generated output, and fixes a bug in DefaultS3CrtAsyncClient where signing attributes were being read before they were resolved.

Modifications

• Updated codegen fixture/expected files to reflect the removal of auth scheme resolution and endpoint resolution logic from generated interceptors.
• DefaultS3CrtAsyncClient: Moved SIGNING_REGION and SERVICE_SIGNING_NAME reads to beforeTransmission where the values are available after pipeline stages have run.
  Previously these were read in afterMarshalling which now runs before auth scheme and endpoint resolution.
• S3Express WireMock tests: Changed endpoint override from localhost to 127.0.0.1. With endpoint resolution now running after modifyHttpRequest interceptors, the PathStyleEnforcingInterceptor can no longer rewrite virtual-hosted URLs. Using an IP-based endpoint causes the S3 endpoint rules to produce path-style URLs directly.

Testing

• Codegen unit tests pass with updated fixtures.
• S3Express integration tests pass with the CRT client fix.
• S3Express integration tests pass with the CRT client signing fix.
• Cross-region CRT integration test passes with correct signing region.