LU-14275 tests: add ior_CLEANUP

LU-14275 tests: add ior_CLEANUP

Sometimes we need to run read IOR test separately from
write test. IOR -r test requires file exists before test starts.
If ior_CLEANUP set to false $testdir is not removed and
$testdir/iorData file can be used for IOR -r further test.

Test-Parameters: trivial testlist=parallel-scale
Signed-off-by: Elena Gryaznova <elena.gryaznova@hpe.com>
HPE-bug-id: LUS-9560
Reviewed-by: Vladimir Saveliev <vladimir.saveliev@hpe.com>
Reviewed-by: Sergey Cheremencev <sergey.cheremencev@hpe.com>
Change-Id: Iac790976a46db2bf5be374a42e3facdce074228b
Reviewed-on: https://review.whamcloud.com/41079
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>