Bug 1857866 - Enable mozilla/no-arbitrary-setTimeout on all of dom/. r=dom-core,mccr8

Differential Revision: https://phabricator.services.mozilla.com/D190433

.eslintrc.js

@@ -433,7 +433,6 @@ module.exports = {
         "consistent-return": "off",
         "mozilla/avoid-removeChild": "off",
         "mozilla/consistent-if-bracing": "off",
-        "mozilla/no-arbitrary-setTimeout": "off",
         "mozilla/no-compare-against-boolean-literals": "off",
         "mozilla/reject-importGlobalProperties": "off",
         "mozilla/use-includes-instead-of-indexOf": "off",

dom/security/test/csp/browser_manifest-src-override-default-src.js

@@ -102,6 +102,7 @@ function createNetObserver(test) {
   const finished = new Promise(resolver => {
     finishedTest = resolver;
   });
+  // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
   const timeoutId = setTimeout(() => {
     if (!success) {
       test.run("This test timed out.");