fix(functional-tests): fix test failures on train 287.1 tag

Because:

* Some functional tests were failing for the tag

This commit:

* Add assertions in the failing tests

Closes #FXA-9909

packages/functional-tests/tests/react-conversion/oauthSignin.spec.ts

@@ -79,6 +79,8 @@ test.describe('severity-1 #smoke', () => {
         `${page.url()}&forceExperiment=generalizedReactApp&forceExperimentGroup=react`
       );
 
+      await expect(page).toHaveURL(/oauth\/signin/);
+      await expect(page.locator('#root')).toBeEnabled();
       await expect(signin.cachedSigninHeading).toBeVisible();
       // Email is prefilled
       await expect(page.getByText(credentials.email)).toBeVisible();

packages/functional-tests/tests/settings/changeEmail.spec.ts

@@ -82,6 +82,7 @@ test.describe('severity-1 #smoke', () => {
       await settings.signOut();
 
       // Sign in with old password
+      await expect(signin.emailFirstHeading).toBeVisible();
       await signin.fillOutEmailFirstForm(newEmail);
       await signin.fillOutPasswordForm(initialPassword);