BUG Fix ModelAdmin search (fixes #8052)

Broken by jQuery UI ajax behaviour in tabs, which compares
URLs to determine if the tab needs to be loaded via ajax.
This was always a brittle solution, and now broke alongside
our upgrade to jQuery UI 1.9 (specifically, with 2657a27).

The ajax behaviour is now globally disabled in favour of
having '.cms-panel-link' behaviour on the tabs, which
was already in place.

admin/javascript/LeftAndMain.js

@@ -923,14 +923,8 @@ jQuery.noConflict();
 				if(!this.data('uiTabs')) this.tabs({
 					active: (activeTab.index() != -1) ? activeTab.index() : 0,
 					beforeLoad: function(e, ui) {
-						// Overwrite ajax loading to use CMS logic instead
-						var makeAbs = $.path.makeUrlAbsolute,
-							baseUrl = $('base').attr('href'),
-							isSame = (makeAbs(ui.ajaxSettings.url, baseUrl) == makeAbs(document.location.href));
-
-						if(!isSame) $('.cms-container').loadPanel(ui.ajaxSettings.url);
-						$(this).tabs('select', ui.tab.index());
-
+						// Disable automatic ajax loading of tabs without matching DOM elements, 
+						// determining if the current URL differs from the tab URL is too error prone.
 						return false;
 					},
 					activate: function(e, ui) {