Cbstats vbucket-details ops_counter increamented twice for subdoc CRUDs

Build: 6.6.0-7687

Steps to reproduce:

1. Single node cluster, Couchbase bucket (replicas=0)
2. Create a document
3. Perform sub_doc insert, upsert, replace and delete (subdoc_read after each operation for verification purpose)

Observation:

After each sub_doc op and read operation, seeing "ops_get" is incremented by the value of '2'.

Also if these are sync_writes, "sync_write_committed_count" is also incremented by '2'

Below is the sample stats when doc_key=nUiCRNw9sUlQ

[root@node1-cb601-centos7 ~]# /opt/couchbase/bin/cbstats -u Administrator -p password localhost:11210 vbucket-details 586 | grep ops

 vb_586:ops_create:                      1

 vb_586:ops_delete:                      0

 vb_586:ops_get:                         8

 vb_586:ops_reject:                      0

 vb_586:ops_update:                      4

Attaching test.logand sub_doc_ops.pcapng for futher investigation.