MB-4460: Don't aggregate a disconnected tap stream
MB-4460: Don't aggregate a disconnected tap stream

When a tap stream is disconnected and then reconnected we create
a dummy tap stream with an anonymous name which is later cleaned
up. These tap connections should not be included in the tap agg
stats.

Change-Id: I044298a55555b803bad67fcf7e033ff6adc57be2
Reviewed-on: http://review.couchbase.org/25409
Reviewed-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>
Tested-by: Michael Wiederhold <a17fed27eaa842282862ff7c1b9c8395a26ac320@couchbase.com>

membase/ep-engine,membase/ep-engine,abhinavdangeti/ep-engine,jimwwalker/ep-engine,teligent-ru/ep-engine,hisundar/ep-engine,daverigby/ep-engine,membase/ep-engine,owendCB/ep-engine,membase/ep-engine,teligent-ru/ep-engine,couchbase/ep-engine,teligent-ru/ep-engine,daverigby/ep-engine,owendCB/ep-engine,abhinavdangeti/ep-engine,daverigby/kv_engine,couchbase/ep-engine,sriganes/ep-engine,teligent-ru/ep-engine,abhinavdangeti/ep-engine,sriganes/ep-engine,owendCB/ep-engine,daverigby/ep-engine,abhinavdangeti/ep-engine,daverigby/kv_engine,couchbase/ep-engine,hisundar/ep-engine,owendCB/ep-engine,daverigby/kv_engine,jimwwalker/ep-engine,hisundar/ep-engine,sriganes/ep-engine,daverigby/kv_engine,jimwwalker/ep-engine,abhinavdangeti/ep-engine,daverigby/ep-engine,sriganes/ep-engine,jimwwalker/ep-engine,couchbase/ep-engine,hisundar/ep-engine