Remove useless removal of ?XDCR_TRACE_LOGGER.

Because it's not part of StdLoggers anyway.

Change-Id: Iecfcddb8e0301988cae6d2bed56717e2e7ce467c
Reviewed-on: http://review.couchbase.org/37741
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Artem Stemkovski <artem@couchbase.com>