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>
MB-7635 Increase synchronization timeout to ns_config_rep_merger.

ns_config_rep:synchronize_remote function uses timeout of 30
seconds. But internally corresponding handle_call clause used default
gen_server timeout (which is 5 seconds) to synchronize with merger
process. This made outer timeout basically useless.

This is exactly what I see in MB-7535 log. For some non-obvious reason
one of the nodes fails to synchronize with merger process within 5
seconds which crashes ns_config_rep process on that node.

Unfortunately I don't know what the merger process was occupied with
for those 5 seconds. Some evidence suggests (e.g. lost ticks messages)
that it may be another manifestation of vm timeouts. Or it may be
something else. Anyway, this change should make the issue less visible.

Change-Id: I867bbe5ba7c3be734a64593f9198be4b5edbcdac
Reviewed-on: http://review.couchbase.org/24360
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Merge remote-tracking branch 'origin/2.0.1'

* origin/2.0.1:
  MB-7635 Increase synchronization timeout to ns_config_rep_merger.
  MB-7603 Improve logging of deletion purge compactions.
  MB-7603 Mention unsafePurgeBucket request type in CHANGES file.
  MB-7618 Cancel delayed compactions when uninhibiting compaction.

Change-Id: I5d1f396aa083805f8814fd17f1a2a62d399d65f3