DDN-2073 tests: fix sanity-sec test_15

DDN-2073 tests: fix sanity-sec test_15

sanity-sec test_15 should not inherit trusted and admin properties for
newly created nodemaps from the default nodemap. Instead, it must
explicitly set both to 0, as the whole point is to exercise id
mappings.

Test-Parameters: trivial testlist=sanity-sec
Test-Parameters: clientdistro=ubuntu2004 testlist=sanity-sec
Change-Id: Ie80a10528268024d59cd079949620ebd1a836395
Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-on: https://review.whamcloud.com/45100
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>