test: fix test scripts filename pattern

In this branch it's testsuite-xy.foo, not TEST-XY-FOO

Follow-up for dffa62c

(cherry picked from commit 14e3284)
(cherry picked from commit 5b199c6)

Author: bluca

test/units/TEST-74-AUX-UTILS.sysusers.sh renamed to test/units/testsuite-74.sysusers.sh

@@ -3,9 +3,6 @@
 set -eux
 set -o pipefail
 
-# shellcheck source=test/units/util.sh
-. "$(dirname "$0")"/util.sh
-
 at_exit() {
     set +e
     userdel -r foobarbaz