feat: Enhanced pgBackRest Support (Sidecar Architecture)

[SBALAVIGNESH123]

I’ve merged the latest changes from v4.x into the branch, ensuring that our pgBackRest implementation remains intact. The merge conflicts in StandalonePostgresql.php were handled manually to preserve the new backup logic while pulling in the upstream model updates, and I accepted the incoming changes for all other unrelated files to keep things clean. I also took the time to address the GitGuardian alert by sanitizing the test credentials and did a quick polish pass on PgBackrestService.php
to remove some verbose comments, so the code looks much more professional now. Everything builds and passes local checks, so it’s ready for review

[gitguardian]

️✅ There are no secrets present in this pull request anymore.

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