MB-11146 Replicate ddocs in a subprocess of capi_set_view_manager.

Because otherwise capi_set_view_manager might get stuck in replication
which in turn will slows down the failover.

Change-Id: Ie8a1f294c175ca5a59a057c91927fe83fd1b5f11
Reviewed-on: http://review.couchbase.org/39035
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Artem Stemkovski <artem@couchbase.com>