test: force resigning of app

In the GitHub Actions CI, test-macos-app-sandbox.js can fail due
to the application already being signed. This commit updates
the test to handle that condition.

Refs: https://github.com/nodejs/node/pull/33944
PR-URL: https://github.com/nodejs/node/pull/34331


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>