fix(server): back off relay client restarts - #8427

Eligibility
This focused server-side fix limits repeated Cloudflare relay respawns with a tested exponential backoff, while preserving immediate explicit configuration reconciliation and guarding against stale restarts. Its production impact is confined to connector recovery after process exits, with no schema, deployment, or sensitive-package changes.

Notes:
No code owners found in target merge base f6f2be3