Hide messages when loading results

This closes https://github.com/select2/select2/issues/3343

src/js/select2/results.js

@@ -48,9 +48,15 @@ define([
       )
     );
 
+    $message[0].className += ' select2-results__message';
+
     this.$results.append($message);
   };
 
+  Results.prototype.hideMessages = function () {
+    this.$results.find('.select2-results__message').remove();
+  };
+
   Results.prototype.append = function (data) {
     this.hideLoading();
 
@@ -250,6 +256,7 @@ define([
     });
 
     container.on('query', function (params) {
+      self.hideMessages();
       self.showLoading(params);
     });