LU-4442 test: add version check for replay-vbr.sh test_7g

LU-4442 test: add version check for replay-vbr.sh test_7g

In replay-vbr.sh test_7g.3, because mdt_object_exists() was added
in http://review.whamcloud.com/#/c/8371, client will not be evicted
without object version check.

The patch also fixes the wrong usage of wait_mds_ost_sync() in
replay_vbr.sh test_7_cycle(). The first parameter should be a timeout
in seconds, not a facet.

Test-Parameters: envdefinitions=SLOW=yes,ONLY=7 testlist=replay-vbr

Signed-off-by: Emoly Liu <emoly.liu@intel.com>
Signed-off-by: Jian Yu <jian.yu@intel.com>
Change-Id: I4a960fc53451fc717370bc96f926f067bbb2946a
Reviewed-on: http://review.whamcloud.com/9290
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>