Fix LocaleTranslatedSchemaDefinitionTest when MINIMUM_SUPPORTED_PHP is used

Go, tests, go.

#3265412: QuickStartTestBase is incompatible with the current implementation of MINIMUM_SUPPORTED_PHP causes the other failures.

So this is another test that tries to do the right thing, but doesn't quite do so successfully:

    // Visit the update page to collect any strings that may be translatable.   
    $user = $this->drupalCreateUser(['administer software updates']);
    $this->drupalLogin($user);
    $update_url = $GLOBALS['base_url'] . '/update.php';
    $this->drupalGet($update_url, ['external' => TRUE]);

    // Ensure that there are no updates just due to translations. Check for     
    // markup and a link instead of specific text because text may be           
    // translated.                                                              
    $this->drupalGet($update_url . '/selection', ['external' => TRUE]);
    $this->updateRequirementsProblem();
    $this->drupalGet($update_url . '/selection', ['external' => TRUE]);
    $this->assertSession()->responseContains('messages--status');
    $this->assertSession()->linkByHrefNotExists('fr/update.php/run', 'No link to run updates.');

The problem on PHP versions lower than \Drupal::MINIMUM_SUPPORTED_PHP is that strings are only collected from the warnings page, and not from the second screen. Moving the $this->updateRequirementsProblem() call earlier, prior to the randomized translation, resolves this.