remove testing ui v2 directory (#2385)

ui-v2/tailwind.config.js

@@ -1,13 +0,0 @@
-/** @type {import('tailwindcss').Config} */
-export default {
-  content: ['./index.html', './src/**/*.{js,ts,jsx,tsx}'],
-  theme: {
-    extend: {
-      colors: {
-        bgApp: 'var(--bg-app)',
-        textProminent: 'var(--text-prominent)',
-      },
-    },
-  },
-  plugins: [],
-};