Bug 1496128 - Fix perma fail in browser/components/newtab/test/browser for search shortcuts r=k88hudson

Each of the tests account for search shortcuts being there, so turning them off was leading to failures. Instead, we'll leave them on, since that will be the default case, and let the tests decide on the behaviour for themselves.

Differential Revision: https://phabricator.services.mozilla.com/D7731

--HG--
extra : moz-landing-system : lando

browser/components/newtab/test/browser/head.js

@@ -19,6 +19,7 @@ async function setDefaultTopSites() { // eslint-disable-line no-unused-vars
   // Toggle the feed off and on as a workaround to read the new prefs.
   await pushPrefs(["browser.newtabpage.activity-stream.feeds.topsites", false]);
   await pushPrefs(["browser.newtabpage.activity-stream.feeds.topsites", true]);
+  await pushPrefs(["browser.newtabpage.activity-stream.improvesearch.topSiteSearchShortcuts", true]);
 }
 
 async function clearHistoryAndBookmarks() { // eslint-disable-line no-unused-vars