MB-14190: Clear the fdb_doc for storing vbucket state information
MB-14190: Clear the fdb_doc for storing vbucket state information

The fdb_doc used to store the vbucket state information in a
separate KV store instance needs to be cleared as garbage data
can result in sporadic errors

Change-Id: I1adbff87c68119c4ddfd56611cd6a15ad96b8f74
Reviewed-on: http://review.couchbase.org/52874
Reviewed-by: abhinav dangeti <d73ef2279de6577f7bf081737ee47554bbb7dc82@couchbase.com>
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

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