LU-15461 test: add stop file check

LU-15461 test: add stop file check

Adding the creation checking of "stop file".

Change-Id: I4acd36e61faf4259c2821293ffb7913d4cca76bd
Test-Parameters: trivial testlist=sanity-quota
Signed-off-by: Hongchao Zhang <hongchao@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/52737
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Sergey Cheremencev <scherementsev@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>