LU-10624 tests: conf-sanity needs larger ZFS filesystems

LU-10624 tests: conf-sanity needs larger ZFS filesystems

otherwise some tests can take a lot (like ~2000 seconds
for test 106) due to very limited space and short
transactions. with the patch 106 passes in ~440 seconds.

Change-Id: I0597072cf72315411b7e656b1e87a0fceabb171f
Signed-off-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-on: https://review.whamcloud.com/31192
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>