Fix 20251 concurrency lease retry

[harshang03]

This PR prevents concurrency lease renewal from crashing flows stuck in AwaitingRetry by keeping deployment leases through retry transitions and treating 404/410 renewals as a clean “lease lost” signal. The client now exposes try_renew_concurrency_lease helpers, the lease renewal loop exits gracefully when a lease is gone, and server release logic skips AwaitingRetry transitions to avoid dropping the lease mid-retry.
ISSUE : #20251

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