LU-14413 test: test for overstriping for sanity 27M

LU-14413 test: test for overstriping for sanity 27M

The introduction of sanity 27M broke interop with 2.12 LTS since
over striping doesn't exist in that version. Adjust the test to
use over striping if the client supports it, otherwise just use
traditional striping.

Lustre-change: https://review.whamcloud.com/44340
Lustre-commit: 4e1f9c4bd1d96063a1fbb2dfaab41b15836167ab

Test-Parameters: trivial testlist=sanity env=ONLY=27M
Change-Id: I2d788a116cbb749a83d6cec36f97d06533b32421
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Emoly Liu <emoly@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/46760
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>