Part 2: Adjust notification tests
Fixing one test to set permission properly and another to not trigger external network request.
Differential Revision: https://phabricator.services.mozilla.com/D198957
bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1878741
gecko-commit: 5ab2cff5dfceaa1f85f4aae5f963b92d65fa517a
gecko-reviewers: asuth, dom-worker-reviewers