test: reenable test for cg_get_keyed_attribute()

The test case was mistakenly disabled by
a412a1b92a.

Co-authored-by: Natalie Vock <natalie.vock@gmx.de>

src/test/test-cgroup-util.c

@@ -432,7 +432,7 @@ TEST(cg_get_keyed_attribute) {
         int r;
 
         r = cg_get_keyed_attribute("cpu", "/init.scope", "no_such_file", STRV_MAKE("no_such_attr"), &val);
-        if (IN_SET(r, -ENOMEDIUM, -ENOENT) || ERRNO_IS_PRIVILEGE(r)) {
+        if (r == -ENOMEDIUM || ERRNO_IS_PRIVILEGE(r)) {
                 log_info_errno(r, "Skipping most of %s, /sys/fs/cgroup not accessible: %m", __func__);
                 return;
         }