Apply partition changes to indexes immediately.

After indexes switched to UPR, there's no need to ensure that vbuckets
physically exist on disk.

Change-Id: I0eb1e9edcfbd941112763bc9cda93ebdc8bab383
Reviewed-on: http://review.couchbase.org/35701
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
MB-10649 Indicate that _all_docs is no longer supported.

Change-Id: Iec87999bc869f641081c7535e5ee89de02c8930b
Reviewed-on: http://review.couchbase.org/35702
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
MB-10715 Prefer vbucket maps that are already in the history.

But only if number of moves is the same.

Change-Id: I53bf99da01dd16edf2e4f07c3ffc93eac5012187
Reviewed-on: http://review.couchbase.org/35703
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
MB-10715 Don't consider map unbalanced if it's in the history.

Change-Id: I26d639a4197097b6c0c1511743f4b899d274f573
Reviewed-on: http://review.couchbase.org/35704
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>