CBQE-0 Fix syntax error in swap_rebalance test

Change-Id: I0847824896894710643508b65b8572884f1a7ee8
Reviewed-on: http://review.couchbase.org/29624
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>