LU-4060 test: skip sanityn.sh test_74 on older than 2.4.93 MDS

LU-4060 test: skip sanityn.sh test_74 on older than 2.4.93 MDS

2.5 client 2.4 server interop testing shows that sanityn.sh
test_74 needs to be skipped for Lustre MDS versions older than
2.4.93 servers.

This patch is for the b2_5 branch.

Signed-off-by: James Nunez <james.a.nunez@intel.com>
Signed-off-by: Emoly Liu <emoly.liu@intel.com>
Change-Id: I8fd414adcf6bb6b7f8b390f1c52e3fea42701d1b
Reviewed-on: http://review.whamcloud.com/8700
Tested-by: Jenkins
Reviewed-by: Jian Yu <jian.yu@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>