MB-7618 Cancel delayed compactions when uninhibiting compaction.

Otherwise we'll receive another 'compact' message when we don't
expect. And what's more, every compaction that we force will schedule
another delayed compaction. And we can end up in a situation when
compaction gets triggered several times during a second.

Change-Id: I52c30bea5805a9a2a8b0ffccfeaf262bd258c7d1
Reviewed-on: http://review.couchbase.org/24257
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-7603 Mention unsafePurgeBucket request type in CHANGES file.

Change-Id: I157d700edf096cf210d1063ec2ee07130c0b4197
Reviewed-on: http://review.couchbase.org/24344
Reviewed-by: Sriram Melkote <siri.couchbase@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-7603 Improve logging of deletion purge compactions.

Change-Id: I238f3d7f720cf518c7a42ab984a229c0818f49f9
Reviewed-on: http://review.couchbase.org/24345
Reviewed-by: Sriram Melkote <siri.couchbase@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>