reindent ns_rebalancer.erl

Some lines were slightly off.

Change-Id: I0002193eb2831c85dea25b50248ff4e5662861f5
Reviewed-on: http://review.couchbase.org/35221
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>