Get rid of some Application methods

These are not necessary to be available so broadly. In fact, they
seem to make it too easy to use them, which has lead to some sub-
optimal architecture decisions.

Their equivalents have been moved to the classes where used.

src/Locale/LocaleServiceProvider.php

@@ -13,6 +13,7 @@ namespace Flarum\Locale;
 
 use Flarum\Event\ConfigureLocales;
 use Flarum\Foundation\AbstractServiceProvider;
+use Flarum\Settings\SettingsRepositoryInterface;
 use Illuminate\Contracts\Events\Dispatcher;
 use Illuminate\Contracts\Translation\Translator as TranslatorContract;
 use Symfony\Component\Translation\MessageSelector;
@@ -54,8 +55,8 @@ class LocaleServiceProvider extends AbstractServiceProvider
 
     private function getDefaultLocale(): string
     {
-        return $this->app->isInstalled() && $this->app->isUpToDate()
-            ? $this->app->make('flarum.settings')->get('default_locale', 'en')
-            : 'en';
+        $repo = $this->app->make(SettingsRepositoryInterface::class);
+
+        return $repo->get('default_locale', 'en');
     }
 }