MB-9096: killed unused handling of old-style mb_master heartbeats
MB-9096: killed unused handling of old-style mb_master heartbeats

Change-Id: Ic9f7cad31f4138df0556dd1d82acfafa5f316eef
Reviewed-on: http://review.couchbase.org/29323
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Artem Stemkovski <15a0730a27c69f62ab86f2b6c639fca202166c02@couchbase.com>

membase/ns_server,daverigby/ns_server,ceejatec/ns_server,ceejatec/ns_server,nimishzynga/ns_server,vzasade/ns_server,mschoch/ns_server,ceejatec/ns_server,vzasade/ns_server,vzasade/ns_server,membase/ns_server,ceejatec/ns_server,nimishzynga/ns_server,daverigby/ns_server,nimishzynga/ns_server,daverigby/ns_server,mschoch/ns_server,mschoch/ns_server,mschoch/ns_server,membase/ns_server,mschoch/ns_server,membase/ns_server,t3rm1n4l/ns_server,daverigby/ns_server,t3rm1n4l/ns_server,nimishzynga/ns_server,t3rm1n4l/ns_server,t3rm1n4l/ns_server,daverigby/ns_server,mschoch/ns_server,ceejatec/ns_server,nimishzynga/ns_server,membase/ns_server,nimishzynga/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,vzasade/ns_server,membase/ns_server