trust varnish headers

Author: eloiferrer

LocalSettings.d/base/cdn.php

@@ -7,4 +7,7 @@
     $wgInternalServer = str_replace('https://', 'http://', $wgServer);
     $wgCdnMaxAge = 18000; // 5 hours (default)
     $wgCdnMaxageLagged = 18000; // MediaWiki incorrectly detects lagged database due to Galera cluster architecture.
-}
+}
+
+# Trust proxy headers from Varnish
+$wgUsePrivateIPs = true;