LU-11912 tests: force new seq in runtests

LU-11912 tests: force new seq in runtests

If seq rollover happens during runtests/1,
the new seq on OST will consume some space and
this will fail the free space check.

Force a new seq before running test case to
prevent this.

Lustre-change: https://review.whamcloud.com/52741
Lustre-commit: TBD

Change-Id: I7bb1156127eb423889626bf84bc6c87dd68e6ece
Test-Parameters: trivial testlist=runtests
Signed-off-by: Li Dongyang <dongyangli@ddn.com>
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/52743
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>