fix: return 204 instead of 404

Signed-off-by: SebastianKrupinski <krupinskis05@gmail.com>

apps/dav/lib/CardDAV/ImageExportPlugin.php

@@ -90,7 +90,7 @@ public function httpGet(RequestInterface $request, ResponseInterface $response)
 
 			$response->setBody($file->getContent());
 		} catch (NotFoundException $e) {
-			$response->setStatus(404);
+			$response->setStatus(204); // 204 No Content
 		}
 
 		return false;