Retried prepare times out while partition is in degraded mode

Since ISPN-5046, prepare commands are retried if one of the prepare targets has left the cluster. However, when the cache enters degraded mode, the prepare targets still include the owners in other partitions, and the prepare command is retried again.

Each retry automatically waits for cache topology <command topology> + 1. But the second retry is not really triggered by a topology change, so the retry blocks for remoteTimeout milliseconds before failing with a TimeoutException.

This situation actually happens in OptimisticTxPartitionAndMergeDuringPrepareTest, but the tests do not fail because it doesn't wait for an AvailabilityException specifically: they just take 15+ seconds each.