Remove generateUniqueID helper

packages/govuk-frontend/src/govuk/common/index.mjs

@@ -8,26 +8,6 @@
  * @module common/index
  */
 
-/**
- * Used to generate a unique string, allows multiple instances of the component
- * without them conflicting with each other.
- * https://stackoverflow.com/a/8809472
- *
- * @deprecated Will be made private in v5.0
- * @returns {string} Unique ID
- */
-export function generateUniqueID () {
-  var d = new Date().getTime()
-  if (typeof window.performance !== 'undefined' && typeof window.performance.now === 'function') {
-    d += window.performance.now() // use high-precision timer if available
-  }
-  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
-    var r = (d + Math.random() * 16) % 16 | 0
-    d = Math.floor(d / 16)
-    return (c === 'x' ? r : (r & 0x3 | 0x8)).toString(16)
-  })
-}
-
 /**
  * Config flattening function
  *

packages/govuk-frontend/src/govuk/common/index.unit.test.mjs

@@ -1,7 +1,5 @@
 import { mergeConfigs, extractConfigByNamespace } from './index.mjs'
 
-// TODO: Write unit tests for `generateUniqueID`
-
 describe('Common JS utilities', () => {
   describe('mergeConfigs', () => {
     const config1 = {