MB-18096 Remove services key prior to joining.
MB-18096 Remove services key prior to joining.

It's being set by the node that initiates node add. But with new logic
that updates vclocks before join, the updated value from the joinee wins
the conflict.

Change-Id: I5b20107a937c2e3878ccdb6eb686d73653ccaf3c
Reviewed-on: http://review.couchbase.org/60220
Tested-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>
Reviewed-by: Artem Stemkovski <15a0730a27c69f62ab86f2b6c639fca202166c02@couchbase.com>

membase/ns_server,membase/ns_server,ceejatec/ns_server,membase/ns_server,ceejatec/ns_server,ceejatec/ns_server,membase/ns_server,ceejatec/ns_server,ceejatec/ns_server,membase/ns_server,membase/ns_server,ceejatec/ns_server