Switch the app to German as its only language

The app is used internally only and its settings page was German
already. Mails, controller error messages (shown in the form), the
settings section name and the mail sender are now written in German
directly instead of going through IL10N without any translation files.
Nextcloud's own mail footer is requested in German as well.

lib/Settings/PersonalSection.php

@@ -5,13 +5,11 @@ declare(strict_types=1);
 namespace OCA\WorkflowDeckAutomation\Settings;
 
 use OCA\WorkflowDeckAutomation\AppInfo\Application;
-use OCP\IL10N;
 use OCP\IURLGenerator;
 use OCP\Settings\IIconSection;
 
 class PersonalSection implements IIconSection {
 	public function __construct(
-		private IL10N $l10n,
 		private IURLGenerator $urlGenerator,
 	) {
 	}
@@ -21,7 +19,8 @@ class PersonalSection implements IIconSection {
 	}
 
 	public function getName(): string {
-		return $this->l10n->t('Deck workflow automation');
+		// German only, like the rest of this internal app.
+		return 'Deck Workflow-Automatisierung';
 	}
 
 	public function getPriority(): int {