strip metrics before persistency
strip metrics before persistency

Change-Id: I235c76b49ee1ea73616b6623fba2b4f6958918c6
Reviewed-on: http://review.couchbase.org/22931
Reviewed-by: Pavel Paulau <dd88eded64e90046a680e3a6c0828ceb8fe8a0e7@gmail.com>
Tested-by: Ronnie Sun <06648be64f8fbc529d817d157ec32d385ea42f22@couchbase.com>

pavel-paulau/cbagent,couchbase/cbmonitor,vmx/cbagent,mikewied/cbagent,ronniedada/litmus,couchbase/cbagent,ronniedada/litmus,couchbase/cbmonitor