MB-6724: ignore nodes without couchApiBase
MB-6724: ignore nodes without couchApiBase

remote_clusters_info code that was grabbing remote bucket info was
insisting on couchApiBase attribute present. Recent change removed
this attribute for nodes without any vbuckets to prevent clients
sending view requests to such nodes.

Thus we have to adapt remote_clusters_info to this node case. We
simply ignore nodes without couchApiBase. The idea is xdcr code will
node need such nodes because as pointed above they dont have any
active vbuckets.

Change-Id: I0660e58164b3a61e1a08578cb7a111cc070cd95c
Reviewed-on: http://review.couchbase.org/21109
Reviewed-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>

mschoch/ns_server,t3rm1n4l/ns_server,vzasade/ns_server,pavel-blagodov/ns_server,ceejatec/ns_server,ceejatec/ns_server,nimishzynga/ns_server,membase/ns_server,nimishzynga/ns_server,pavel-blagodov/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,pavel-blagodov/ns_server,pavel-blagodov/ns_server,ceejatec/ns_server,mschoch/ns_server,membase/ns_server,daverigby/ns_server,t3rm1n4l/ns_server,mschoch/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,mschoch/ns_server,membase/ns_server,daverigby/ns_server,mschoch/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,vzasade/ns_server,daverigby/ns_server,vzasade/ns_server,daverigby/ns_server,nimishzynga/ns_server,mschoch/ns_server,ceejatec/ns_server,vzasade/ns_server,t3rm1n4l/ns_server,daverigby/ns_server,membase/ns_server,nimishzynga/ns_server,membase/ns_server,membase/ns_server