Use fixed timezone in UserPref test

Author: Timshel

playwright/e2e/settings/preferences-user-settings-tab.spec.ts

@@ -17,6 +17,11 @@ limitations under the License.
 
 import { test, expect } from "../../element-web-test";
 
+test.use({
+  locale: 'en-GB',
+  timezoneId: 'Europe/London',
+});
+
 test.describe("Preferences user settings tab", () => {
     test.use({
         displayName: "Bob",