use infinite timeout in work_queue:submit_sync_work/2

I.e. default timeout of 5 seconds is just too low.

Change-Id: Iead7d0840715b9845d5dcf66506c52bc698ae65d
Reviewed-on: http://review.couchbase.org/31691
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>