Flusher needs to account for Sync Messages from Projector

Once the Where clause becomes functional in Projector, all mutations will not reach all indexers. So there may be scenario where a snapshot marker has come for lets say vbucket 10 which start = 10 and end = 50. Indexer will generate stability timestamp and wait for mutation with seqno 50. But if mutations get filtered out due to Where, these mutations may never come.

Flusher needs to check if Sync messages till that seqno has come, it means the mutation was skipped and flush can be completed.