LU-8995 tests: set debug size correctly

LU-8995 tests: set debug size correctly

Use library function to set the debug log size

Seagate-bug-id: MRP-4055
Signed-off-by: Alexey Lyashkov <alexey.lyashkov@seagate.com>
Signed-off-by: Parinay Kondekar <Parinay.Kondekar@seagate.com>
Change-Id: I125ce7f5f7f7754e82f913ef8cf6944f40f631d6
Reviewed-on: https://review.whamcloud.com/24782
Reviewed-by: Jian Yu <jian.yu@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>