loading icon sometimes toggled alongside MR pipeline contents

unbind existing listenerss and remove duplicate MiniPipelineGraph init

app/assets/javascripts/merge_request_widget.js.es6

@@ -252,7 +252,6 @@ require('./smart_interval');
         $('.ci_widget.ci-error').show();
         this.setMergeButtonClass('btn-danger');
       }
-      this.initMiniPipelineGraph();
     };
 
     MergeRequestWidget.prototype.showCICoverage = function(coverage) {

app/assets/javascripts/mini_pipeline_graph_dropdown.js.es6

@@ -28,7 +28,7 @@
      * All dropdown events are fired at the .dropdown-menu's parent element.
      */
     bindEvents() {
-      $(document).on('shown.bs.dropdown', this.container, this.getBuildsList);
+      $(document).off('shown.bs.dropdown', this.container).on('shown.bs.dropdown', this.container, this.getBuildsList);
     }
 
     /**