Fix only builtins fail test

With `config-file=/dev/null` the linting fails with `syntax-check[specific]`
and the only-builtins part is never executed.
Use the global config which properly mocks the fake collection and
assert we raised a warning, not a failure.

Fixes: 6e31f19

src/ansiblelint/rules/only_builtins.py

@@ -48,10 +48,9 @@ def matchtask(
       ansible.builtin.shell: echo This rule should not get matched by the only-builtins rule
     """
 
-    def test_only_builtin_fail() -> None:
+    def test_only_builtins_fail() -> None:
         """Test rule matches."""
         result = run_ansible_lint(
-            "--config-file=/dev/null",
             "--strict",
             "--warn-list=",
             "--enable-list",
@@ -60,8 +59,8 @@ def test_only_builtin_fail() -> None:
         )
         assert result.returncode == VIOLATIONS_FOUND_RC
         assert "Failed" in result.stderr
-        assert "1 failure(s)" in result.stderr
-        assert "only-builtins" in result.stdout
+        assert "1 warning(s)" in result.stderr
+        assert "only-builtins: Use only builtin actions" in result.stdout
 
     @pytest.mark.parametrize(
         "rule_runner", (OnlyBuiltinsRule,), indirect=["rule_runner"]