LU-4270 test: fix sanity test_209

LU-4270 test: fix sanity test_209

Fix the connect_flags checking in test_209 of sanity.sh

This patch is back-ported from the following one:
Lustre-commit: b498499104af17da081f1c22b9c07951104846a3
Lustre-change: http://review.whamcloud.com/8326

Test-Parameters: envdefinitions=SLOW=yes,ENABLE_QUOTA=yes,ONLY=209 \
ossjob=lustre-b2_4 mdsjob=lustre-b2_4 ossbuildno=70 mdsbuildno=70 \
testlist=sanity

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Signed-off-by: Jian Yu <jian.yu@intel.com>
Change-Id: I6c34b9dbe6d3b7475d85588e7adb3acb762fab32
Reviewed-on: http://review.whamcloud.com/8729
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>