[dst] Avoid conflict resolution if waiting transaction is unblocked from unresolvable conflict

[robertsami]

Jira Link: DB-3156 See: https://github.com/yugabyte/yugabyte-db/blob/master/src/yb/docdb/wait_queue.cc#L352 https://github.com/yugabyte/yugabyte-db/blob/master/src/yb/docdb/conflict_resolution.cc#L656

Instead of re-running conflict resolution in these cases, just rollback the transaction and fail the operation