MB-12210: send capi_replication messages to xdcr log

Change-Id: If51a9aad13acdf3e381b3af6b469974d941d1ae9
Reviewed-on: http://review.couchbase.org/42532
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>