Always load authentication apps

The current code path may trigger situations where the LDAP application is not yet loaded and thus problems with the authentication appeared.

In previous versions of ownCloud the authentication mechanism manually loaded these apps which is why this affects ownCloud 8 and master only for my knowledge. (certainly not 6, maybe 7)

Backport to 8 might be something to consider.

Fixes https://github.com/owncloud/core/issues/14469

lib/base.php

@@ -797,6 +797,9 @@ class OC {
 			self::checkUpgrade();
 		}
 
+		// Always load authentication apps
+		OC_App::loadApps(['authentication']);
+
 		// Load minimum set of apps
 		if (!self::checkUpgrade(false)
 			&& !$systemConfig->getValue('maintenance', false)
@@ -805,8 +808,7 @@ class OC {
 			if(OC_User::isLoggedIn()) {
 				OC_App::loadApps();
 			} else {
-				// For guests: Load only authentication, filesystem and logging
+				// For guests: Load only filesystem and logging
-				OC_App::loadApps(array('authentication'));
 				OC_App::loadApps(array('filesystem', 'logging'));
 				\OC_User::tryBasicAuthLogin();
 			}
@@ -815,7 +817,6 @@ class OC {
 		if (!self::$CLI and (!isset($_GET["logout"]) or ($_GET["logout"] !== 'true'))) {
 			try {
 				if (!$systemConfig->getValue('maintenance', false) && !\OCP\Util::needUpgrade()) {
-					OC_App::loadApps(array('authentication'));
 					OC_App::loadApps(array('filesystem', 'logging'));
 					OC_App::loadApps();
 				}