test(radio): skip flaky radio tabbing test (#28668)

Skips the keyboard navigation test in the radio a11y due to it being
flaky:
https://github.com/ionic-team/ionic-framework/actions/runs/7131071726

core/src/components/radio/test/a11y/radio.e2e.ts

@@ -15,7 +15,8 @@ configs({ modes: ['ios'], directions: ['ltr'] }).forEach(({ title, config }) =>
     });
   });
 
-  test.describe(title('radio: keyboard navigation'), () => {
+  // TODO(FW-5715): re-enable test
+  test.skip(title('radio: keyboard navigation'), () => {
     test.beforeEach(async ({ page }) => {
       await page.setContent(
         `