Remove obsolete trusted directives

All supported browsers now have the concept of priviledged
pages, there is no need for these extra trusted-site directives.

Related issue:
uBlockOrigin/uBlock-issues#3101

src/js/background.js

@@ -168,14 +168,8 @@ const µBlock = {  // jshint ignore:line
     netWhitelist: new Map(),
     netWhitelistModifyTime: 0,
     netWhitelistDefault: [
-        'about-scheme',
         'chrome-extension-scheme',
-        'chrome-scheme',
-        'edge-scheme',
         'moz-extension-scheme',
-        'opera-scheme',
-        'vivaldi-scheme',
-        'wyciwyg-scheme',   // Firefox's "What-You-Cache-Is-What-You-Get"
     ],
 
     localSettings: {