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/boards/boardArchive.js

@@ -5,10 +5,6 @@ Template.boardListHeaderBar.events({
 });
 
 BlazeComponent.extendComponent({
-  template() {
-    return 'archivedBoards';
-  },
-
   onCreated() {
     this.subscribe('archivedBoards');
   },