Improve XDS translator test to remove explicit test case definition

[UtkarshUmre]

What type of PR is this?

refactor: Improve XDS translator test to dynamically generate test cases

What this PR does / why we need it:

This PR refactors the XDS translator test to dynamically generate test cases based on input files found in the testdata/xds-ir directory. Instead of explicitly specifying test names and cases within the test function, the code now iterates over input files, treating each file as a separate test case. This approach simplifies the test code, reduces redundancy, and improves maintainability by eliminating the need to specify test names manually.

Which issue(s) this PR fixes:

Fixes #2229

[shawnh2]

hi @UtkarshUmre, thanks for the contribution, can you fix the ci please?

[github-actions[bot]]

This pull request has been automatically marked as stale because it has not had activity in the last 30 days. Please feel free to give a status update now, ping for review, when it's ready. Thank you for your contributions!

[shawnh2]

Since this PR is stale, I will take it from here.