MB-11741: Better scheduling of checkpointRemoverTask

Waking up the checkpoint Remover Task once the cursors
complete parsing a checkpoint till the end, helps
prevent retaining blob instances for a longer time
than necessary.

Change-Id: Ieb1435dafac2e9b9984664218d6761c6c807333a
Reviewed-on: http://review.couchbase.org/40355
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Reviewed-by: Sundararaman Sridharan <sundar@couchbase.com>
Tested-by: abhinav dangeti <abhinav@couchbase.com>
MB-11887: Properly send the snapshot start and end seqnos

Currently we always set the snapshot start and end seqno to be the
same as the start seqno. This is incorrect if we recently were
disconnected and need to resume from a partial snapshot.

Change-Id: I7c9430e0b24ef01cc427cb03b518f4c41a55d875