Merge pull request #55077 from nextcloud/backport/55006/stable31

[stable31] fix(ownCloud): ensure that `accounts.display_name` fits into `users.displayname`

Author: AndyScherzinger

lib/private/Repair/Owncloud/SaveAccountsTableData.php

@@ -172,7 +172,8 @@ protected function migrateUserInfo(IQueryBuilder $update, $userdata) {
 		}
 
 		if ($userdata['display_name'] !== null) {
-			$update->setParameter('displayname', $userdata['display_name'])
+			// user.displayname only allows 64 characters but old accounts.display_name allowed 255 characters
+			$update->setParameter('displayname', mb_substr($userdata['display_name'], 0, 64))
 				->setParameter('userid', $userdata['user_id']);
 			$update->execute();
 		}