[wdspec] Resume blocked requests from the setup_blocked_request fixture on teardown
Hanging blocked requests lead to intermittent failures on mac os debug CI due to too many open files.
Updates the setup_blocked_request to fail requests (or cancel the auth for auth requests).
Differential Revision: https://phabricator.services.mozilla.com/D218048
bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1910555
gecko-commit: 6e0305e8f0940b0bfb8f56c0b7626b1db23305d5
gecko-reviewers: webdriver-reviewers, whimboo