Remove duplicate tracking helper for tests

- no need to edit 2 files, we'll maintain one
  for the future under jest area.

spec/javascripts/helpers/tracking_helper.js

-import Tracking from '~/tracking';
+// No new code should be added to this file. Instead, modify the
+// file this one re-exports from. For more detail about why, see:
+// https://gitlab.com/gitlab-org/gitlab-foss/merge_requests/31349
 
-export default Tracking;
-
-let document;
-let handlers;
-
-export function mockTracking(category = '_category_', documentOverride, spyMethod) {
-  document = documentOverride || window.document;
-  window.snowplow = () => {};
-  handlers = Tracking.bindDocument(category, document);
-  return spyMethod ? spyMethod(Tracking, 'event') : null;
-}
-
-export function unmockTracking() {
-  window.snowplow = undefined;
-  handlers.forEach(event => document.removeEventListener(event.name, event.func));
-}
-
-export function triggerEvent(selectorOrEl, eventName = 'click') {
-  const event = new Event(eventName, { bubbles: true });
-  const el = typeof selectorOrEl === 'string' ? document.querySelector(selectorOrEl) : selectorOrEl;
-
-  el.dispatchEvent(event);
-}
+export * from '../../frontend/helpers/tracking_helper';