EX-7509 tests: enable neterror logging in sanity-benchmark/iozone

EX-7509 tests: enable neterror logging in sanity-benchmark/iozone

This patch enables LNet error logging in sanity-benchmark test_iozone()
to gather network errors while connection issue occurs.

Test-Parameters: trivial env=SLOW=yes,ENABLE_QUOTA=yes \
 clientdistro=el8.6 serverdistro=el7.9 testlist=sanity-benchmark

Change-Id: I398779abc95525fe5579fc7505e6e6221c32bf90
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/51483
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>