LU-8790 test: Limit lock number by available inodes count

LU-8790 test: Limit lock number by available inodes count

For machines with big numbers of CPUs the count of files to create
is more than available inodes. So, the sanity::test_124b fails.

Test-Parameters: trivial

Change-Id: I544efbc0da7acc99f4f60010cb404d234b1db964
Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-on: https://review.whamcloud.com/23543
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>