(core) Remove code related to newui

Summary: Change code that conditionally depended on #newui in the URL to assume that everything is always in the new UI now.

Test Plan: this

Reviewers: dsagal

Reviewed By: dsagal

Subscribers: dsagal

Differential Revision: https://phab.getgrist.com/D3246

app/client/components/DetailView.js

@@ -331,7 +331,6 @@ DetailView.prototype.buildTitleControls = function() {
     kd.maybe(this.recordLayout.layoutEditor, (editor) => editor.buildEditorDom()),
 
     kd.maybe(showControls, () => dom('div.grist-single-record__menu.flexhbox.flexnone',
-      this.gristDoc.app.addNewUIClass(),
       dom('div.grist-single-record__menu__count.flexitem',
         // Total should not include the add record row
         kd.text(() => this._isAddRow() ? 'Add record' :