Update gradle version, fix flaky integration tests, and add cleanup job

[rohanshah18]

Problem

1. Integration tests have been failing
2. submit-gradle job was failing because it used java 21 with incompatible gradle version.

Solution

1. Fix flaky integration tests
2. Add cleanup job that deletes all indexes after integration tests are completed (regardless of success/failure of the job)
3. Update gradle version to 8.5 for all workflows

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Infrastructure change (CI configs, etc)
• Non-code change (docs, etc)
• None of the above: (explain here)

Test Plan

Integration tests should run successfully

[austin-denoble]

There's a small chance the index may not be deletable if it's stuck in an upgrading or stuck or something like that. It might be nice to add a try catch here and explicitly handle possible errors on delete to make sure the cleanup process continues to other indexes.