tests/systemd-user-config: Handle default settings

The test now gracefully handles changes in the systemd module

tests/modules/systemd/user-config.nix

@@ -13,13 +13,9 @@
   nmt.script = ''
     userConf=home-files/.config/systemd/user.conf
     assertFileExists $userConf
-    assertFileContent $userConf ${
-      pkgs.writeText "expected" ''
-        [Manager]
-        DefaultCPUAccounting=true
-        DefaultEnvironment=PATH='/bin:/sbin:/some where' TEST='abc'
-        LogLevel=debug
-      ''
-    }
+    [ "$(head -n1 "$TESTED/$userConf")" == "[Manager]" ] || exit 1
+    assertFileContains $userConf DefaultCPUAccounting=true
+    assertFileContains $userConf LogLevel=debug
+    assertFileRegex $userConf "^DefaultEnvironment=.*PATH='/bin:/sbin:/some where' .*TEST='abc'"
   '';
 }