fix(s3): add support for uppercase characters in legacy bucket names

[5d]

Issue # (if applicable)

Closes #31731

Reason for this change

As @GavinZZ commented in issue #31731, the official AWS S3 documentation stated that uppercase characters were permitted in bucket names prior to March 1, 2018.

Description of changes

• add support for uppercase characters in legacy bucket names

Description of how you validated changes

• added new unit test cases and updated the integration test cases with legacy bucket names

Checklist

• [x] My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

---

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