CBG-1219 Include NODE_DEFS_WANTED in heartbeat node set (#4883)
CBG-1219 Include NODE_DEFS_WANTED in heartbeat node set (#4883)

Ensures that mismatches between NODE_DEFS_WANTED and NODE_DEFS_KNOWN doesn't result in unassigned vbucket partitions.
couchbaselabs/sync_gateway,couchbaselabs/sync_gateway,couchbaselabs/sync_gateway,couchbaselabs/sync_gateway