js/loader: remove pending request on form redirect

Our redirection helper catching forms redirecting to their source
while being shown right-hand left a pending request. Abort was triggered,
but had no effect as the request has already been completed.

fixes #6619

public/js/icinga/loader.js

@@ -260,6 +260,7 @@
                     if ($('#col1').data('icingaUrl') === redirect) {
                         icinga.ui.layout1col();
                         req.$target = $('#col1');
+                        delete(this.requests['col2']);
                     }
                 }