Add failpoint to surface idempotency issues of transaction operations in initial sync

We should be able to handle all idempotency issues when applying transaction operations during initial sync instead of relying on restarting initial sync. However, due to known idempotency issues for other cases, we have to allow multiple initial sync attempts in initial sync fuzzer test. That will mask unexpected failures of transaction operations.

We will add a failpoint to fassert if idempotency issues happen on transaction operations, so that initial sync fuzzer can turn it on and expose such failures.