LU-16642 tests: improve sanity-sec test_61

LU-16642 tests: improve sanity-sec test_61

Improve sanity-sec test_61 by using a client-specific nodemap rather
than the default nodemap.

Test-Parameters: trivial testlist=sanity-sec
Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: Ie0c9e381e42a93d89558947dee9a60537cf01e65
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50317
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Sergey Cheremencev <scherementsev@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>