removed js used for early testing

wagtail/wagtailadmin/static/wagtailadmin/js/blocks/chooser.js

@@ -1,9 +0,0 @@
-(function($) {
-    window.Chooser = function(definitionPrefix) {
-        return function(elementPrefix) {
-            $('#' + elementPrefix + '-button').click(function() {
-                alert('hello, I am a chooser for ' + elementPrefix + ', which is of type ' + definitionPrefix);
-            });
-        };
-    };
-})(jQuery);