Updated tests to mock new immutable window location object

tests/javascripts/support/polyfills.js

@@ -1,17 +0,0 @@
-// Polyfills for any parts of the DOM API available in browsers but not JSDOM
-
-let _location = {
-  reload: jest.fn(),
-  hostname: "beta.notify.gov",
-  assign: jest.fn(),
-  href: "https://beta.notify.gov",
-}
-
-// JSDOM provides a read-only window.location, which does not allow for
-// mocking or setting.
-Object.defineProperty(window, 'location', {
-  get: () => _location,
-  set: (value) => {
-    _location = value
-  },
-})