[BP 7.2.7] XDCR - Prevent unexpected stream-requests to local VBs not in 'active' state

CBSE-17642 shows an incident wherein XDCR incorrectly sent a stream-request to a 'dead' state VB, since it was reflected as 'active' in the the vBucketMap from the response  ns_server 'GET /pools/default/bucket'.

By setting the ACTIVE_VB_ONLY flag in our stream-request, we can direct the server to only accept the request if it has the 'active' VB. If not, the request fails with a NOT_MY_VBUCKET error.

Refer flags section of https://github.com/couchbase/kv_engine/blob/master/docs/dcp/documentation/commands/stream-request.md