[bp] Drop parts of ns_connection_pool that we don't use.
[bp] Drop parts of ns_connection_pool that we don't use.

Change-Id: If9c1e115fd91c1f4e649722ba1f5227641f29609
Original-Change-Id: If14333b9c3801f77ea8013ae298013d0206c5d63
Original-Reviewed-on: http://review.couchbase.org/46984
Reviewed-on: http://review.couchbase.org/51760
Reviewed-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>
Tested-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>

membase/ns_server,mschoch/ns_server,membase/ns_server,nimishzynga/ns_server,membase/ns_server,ceejatec/ns_server,membase/ns_server,ceejatec/ns_server,ceejatec/ns_server,membase/ns_server,mschoch/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,ceejatec/ns_server,membase/ns_server,mschoch/ns_server,nimishzynga/ns_server,mschoch/ns_server,ceejatec/ns_server,mschoch/ns_server,nimishzynga/ns_server,ceejatec/ns_server,nimishzynga/ns_server,mschoch/ns_server