Fix default language detection for calendar notifications

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Author: ChristophWurst

apps/dav/lib/CalDAV/Reminder/NotificationProvider/AbstractProvider.php

@@ -104,7 +104,7 @@ protected function getFallbackLanguage():string {
 			return $this->fallbackLanguage;
 		}
 
-		$fallbackLanguage = $this->l10nFactory->findLanguage();
+		$fallbackLanguage = $this->l10nFactory->findGenericLanguage();
 		$this->fallbackLanguage = $fallbackLanguage;
 
 		return $fallbackLanguage;

apps/dav/tests/unit/CalDAV/Reminder/NotificationProvider/EmailProviderTest.php

@@ -104,7 +104,7 @@ public function testSendWithoutAttendees():void {
 			]);
 
 		$this->l10nFactory
-			->method('findLanguage')
+			->method('findGenericLanguage')
 			->willReturn('en');
 
 		$this->l10nFactory
@@ -214,7 +214,7 @@ public function testSendWithAttendees(): void {
 			]);
 
 		$this->l10nFactory
-			->method('findLanguage')
+			->method('findGenericLanguage')
 			->willReturn('en');
 
 		$this->l10nFactory