MB-5904 remove passwords from XDCR logs

this removes only explicit logging of passwords

if you will start doing funny stuff during the
replication (like deleting buckets),
xdcr will start crashing a lot dumping
the state of different processes to the log files
with a lot of passwords in it. I don't see any solution
for this which doesn't require xdcr code rewriting

Change-Id: I104a58a756b4422ddd83a995b9cd115358f1a3d0
Reviewed-on: http://review.couchbase.org/28043
Reviewed-by: Artem Stemkovski <artem@couchbase.com>
Tested-by: Artem Stemkovski <artem@couchbase.com>