Drop service_api connection if handle_connection fails.
Drop service_api connection if handle_connection fails.

In MB-19037 that would happen because cbft never replied to the
initial GetTaskList request. Not sure if dropping the connection would
help, but at least worth trying.

Change-Id: Ic7a8796333a879e427bb4758755a13707ed3974c
Reviewed-on: http://review.couchbase.org/63122
Tested-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>
Reviewed-by: Artem Stemkovski <15a0730a27c69f62ab86f2b6c639fca202166c02@couchbase.com>

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