tests: weighted-rebalance.t shouldn't write to '/dev/tty'

On our jenkins instance "/dev/tty" doesn't exist, necessary
output fails as below message

~~~
./tests/features/weighted-rebalance.t: \
         line 72: /dev/tty: No such device or address
~~~

Comment out the debugging code

Change-Id: Iba29b80c8ba2dcaab3d6654d7c54332a915bffb8
BUG: 1114680
Signed-off-by: Harshavardhana <harsha@harshavardhana.net>
Reviewed-on: http://review.gluster.org/8421
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>