LU-7550 tests: wait OSTs up in check_seq_oid()

LU-7550 tests: wait OSTs up in check_seq_oid()

This patch fixes check_seq_oid() to wait for OST up after it's
restarted.

Test-Parameters: envdefinitions=ONLY=27 \
testlist=sanity,sanity,sanity,sanity

Test-Parameters: envdefinitions=ONLY=27 \
mdtfilesystemtype=zfs mdsfilesystemtype=zfs ostfilesystemtype=zfs \
testlist=sanity,sanity,sanity,sanity

Test-Parameters: envdefinitions=ONLY=27 \
mdtcount=4 testlist=sanity,sanity,sanity,sanity

Signed-off-by: Jian Yu <jian.yu@intel.com>
Change-Id: I1bab1749f041b7fdbd7f78fa5f5e312586b5cc8c
Reviewed-on: http://review.whamcloud.com/17691
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Emoly Liu <emoly.liu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>