JCBC-375: Correctly reorder resubscriber to prevent race condition.

This changeset makes sure that the old reconfigurable is taken out
of the old provider before it gets shut down to avoid a situation
where it is null, leading to failures on subsequent reconnect
attempts.

Change-Id: I733ae5ecc0965a95299dbe5a8b9ca4f25742be31
Reviewed-on: http://review.couchbase.org/30010
Reviewed-by: Michael Nitschinger <michael.nitschinger@couchbase.com>
Tested-by: Michael Nitschinger <michael.nitschinger@couchbase.com>