LU-16683 tests: fix sanity-sec test_61 for SSK

LU-16683 tests: fix sanity-sec test_61 for SSK

When SHARED_KEY is in use, nodemap specific shared keys must be loaded
explicitly because sanity-sec test_61 defines a nodemap dedicated to
the client.

Fixes: a7222127c7 ("LU-16642 tests: improve sanity-sec test_61")
Test-Parameters: trivial
Test-Parameters: testlist=sanity-sec env=ONLY=61
Test-Parameters: testlist=sanity-sec env=SHARED_KEY=true,ONLY=61
Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I206205496352b6f36341c8b962bb7de4b71541d5
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50476
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>