LU-12175 tests: Partial revert of LU-11636

LU-12175 tests: Partial revert of LU-11636

Since landing:
LU-11636/https://review.whamcloud.com/33611/
07b271c0972757772a129e9a6370dbb163f16a06

we have seen high failure rates in several tests:
sanity 208 (LU-12175)
sanity 133g (LU-12171)
recovery-small 107 (LU-12176)
recovery-small 134 (LU-11560)

Testing with a full revert of LU-11636 showed that removing
it stops those failure.  Our best guess is that the
randomization of stripe count and mdt index is the cause,
so this patch reverts just those changes.

Test-Parameters: trivial
Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: Id6fa3079e29178555827f4e1f39d51cf8d62cf31
Reviewed-on: https://review.whamcloud.com/34705
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>