ci: remove hardcoded Gradle version and rely on Gradle wrapper

[Mansi-mParticle]

Background

• The CI workflows were explicitly using a hardcoded Gradle version, which caused mismatches after upgrading the project to Gradle 8.x. This resulted in CI failures even though local builds were passing.

What Has Changed

• Removed the hardcoded gradle-version from GitHub Actions workflows.
• Ensured CI and local builds use the same Gradle version

Screenshots/Video

• {Include any screenshots or video demonstrating the new feature or fix, if applicable}

Checklist

• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• I have added tests that prove my fix is effective or that my feature works.
• I have tested this locally.

Additional Notes

• {Any additional information or context relevant to this PR}

Reference Issue (For employees only. Ignore if you are an outside contributor)

• Closes https://go/j/[ticket-number]