[BUG] [Segment Replication] Replica shard's translog is not getting purged after flush on index

[Rishikesh1159]

Describe the bug
With Segment Replication enabled when a flush is done on index, replica shards are not purging their translog and replica's translog size is increasing with new segment files. This can lead to disk running out of space on node very quickly. This only happens with replica shards, primary shards do purge their translog on a flush.

To Reproduce
Steps to reproduce the behavior:
-> Run a cluster and create an index with segment replication enabled.
-> Insert few docs, then flush on the index.
-> Compare the translog size on disk of primary and replica.

Expected behavior
Same as primary shards replica shards should also purge their translog after a flush on index.