Fix stuck leases when worker restarts with pending checkpoint leases

[chenylee-aws]

Description of changes:

During graceful lease handoff from Worker A to Worker B, a lease can become stuck in a pending checkpoint state when Worker A fails to complete the checkpoint (e.g., due to spurious retries). This leaves the lease with checkpointOwner set to Worker A and leaseOwner set to Worker B.(A valid state)

If Worker B is running, it will not try to acquire the lease because it sees the lease is in pending checkpoint state and leaseDiscover would prevent it to acquire the lease. However, if Worker B restarts and initializes its
LeaseCoordinator, it discovers this lease during the initialize() call. The worker incorrectly acquires and immediately attempts to shut down the lease. The shutdown logic fails to release the lease because the worker never explicitly drops it, causing the heartbeat to continue indefinitely and leaving the lease stuck.

The change adds logic in the initialize method to also not acquire pendingCheckpoint leases as done in leaseDiscoverer. It also adds logic to not renew leases that's not in an expected state

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