LU-7813 tests: clean up ost-pools.sh

LU-7813 tests: clean up ost-pools.sh

Clean up the tests in ost-pools.sh to drop archaic use of
"lfs getstripe -v" that parses the output text in favour of
using options for "lfs getstripe -c" for OST count.

Add the check for newly-created dir/file being in the pool
into create_dir() and create_file().

Test-Parameters: trivial testlist=ost-pools

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: James Nunez <james.a.nunez@intel.com>
Change-Id: Ib2df663a62f89df48a70d07702b41f05f0194ef9
Reviewed-on: http://review.whamcloud.com/18889
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Saurabh Tandan <saurabh.tandan@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>