Update check with correct exit-code handling

Updates the check for inactive state having been preserved to expect a
non-zero exit code - "systemctl is-active" actually returns 3 and the
docs just say that if the service isn't active the return code is
non-zero

Author: barneysowood

tests/pytests/pkg/upgrade/test_systemd_permissions.py

@@ -124,7 +124,7 @@ def test_salt_systemd_inactive_preservation(
         test_cmd = f"systemctl is-active {test_item}"
         ret = salt_call_cli.run("--local", "cmd.run", test_cmd)
         test_active = ret.stdout.strip().split()[2].strip('"').strip()
-        assert ret.returncode == 1
+        assert ret.returncode != 0
         assert test_active == "inactive"