Add fail test for accounts_root_gid_zero

Avoid -o flag since it's used with -u flag

linux_os/guide/system/accounts/accounts-restrictions/root_logins/accounts_root_gid_zero/tests/other_user_uid_0.fail.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+# Remediation doesn't fix the rule, only locks passwords
+# of non-root accounts with uid 0.
+# remediation = none
+
+useradd --gid 0 root2