Remove unnecessary template name declaration

This code was duplicate with the name we use to `register` the
component. A update of blaze-component removed the need to duplicate
this declaration.

client/components/lists/listHeader.js

@@ -1,8 +1,4 @@
 BlazeComponent.extendComponent({
-  template() {
-    return 'listHeader';
-  },
-
   editTitle(evt) {
     evt.preventDefault();
     const newTitle = this.childComponents('inlinedForm')[0].getValue().trim();