Split TestReplicationDroppedTables

It is flaky in pre commit for a long time, usually because of time out. But it always pass for me locally, as well as in nightly job(that's also why it does not in the flaky list

It has 4 tests, not sure which one is the criminal, so I think we could split it into 4 standalone tests, so if it still fails, we can find out the actual flaky one.