Refactor: cts-cli: Avoid nvpair without value

Update an AclTest so that it tries to drop the optional description
attribute from a resource, rather than dropping the value from an
nvpair. value will soon be required for nvpairs.

This requires creating another resource as root, to avoid interfering
with other tests.

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>