Bug 1671983 - Part 3: E10SUtils.jsm isn't loaded in content anymore, r=annyG

Previously this component was loaded in content due to shouldLoadURI requiring
it, but it is no longer required for that, so can be removed from content
processes.

Differential Revision: https://phabricator.services.mozilla.com/D94640

browser/base/content/test/performance/browser_startup_content.js

@@ -41,7 +41,6 @@ const known_scripts = {
     "resource:///actors/LinkHandlerChild.jsm",
     "resource:///actors/PageStyleChild.jsm",
     "resource:///actors/SearchTelemetryChild.jsm",
-    "resource://gre/modules/E10SUtils.jsm",
     "resource://gre/modules/Readerable.jsm",
 
     // Telemetry