MB-5588 check if data traffic is enabled when evaluating degraded mode
MB-5588 check if data traffic is enabled when evaluating degraded mode

Engine has new warmup status, trafficEnabled, which evaluates data
traffic mode (enabled/disabled). Check this status as part of evaluating
Engine's degraded mode within isDegradedMode()

Change-Id: I1b5ba146c6e798fdf180f5b484074c1e65e06cb1
Reviewed-on: http://review.couchbase.org/17342
Reviewed-by: Liang Guo <863407acb9e207441ec9e80d0debd4fe4489aa9b@couchbase.com>
Reviewed-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>
Tested-by: Jin Lim <c45cd80a556f432a3607171a6818cd5a074b5cd4@couchbase.com>

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