LU-8670 tests: test_115 Fixes & Improvements

LU-8670 tests: test_115 Fixes & Improvements

This patch address below points in sanity test_115.
- Do not skip the test when OST is remote.
- Fail Test if ll_ost_io thread has not started.
- Fail Test if ll_os_io  post count is less then
equal to ll_ost_io pre count.
- Fail Test if the count of started thread more
than thread_max.

Test-Parameters: trivial envdefinitions=SLOW=yes testlist=sanity
Signed-off-by: Arshad Hussain <arshad.hussain@seagate.com>
Signed-off-by: Elena V. Gryaznova <elena.gryaznova@seagate.com>
Seagate-bug-id: MRP-981
Change-Id: I51e434a15ee78db59ea5c091b3ec7d7fcf0bab64
Reviewed-by: Ashish Purkar <ashish.purkar@seagate.com>
Reviewed-by: Vladimir Saveliev <vladimir.saveliev@seagate.com>
Reviewed-on: https://review.whamcloud.com/22950
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>