952308ae86
Now that we're no longer testing FOG init instrumentation via rust-in-gtest, we need a new thing to test in this manner or we'll delete this code and (in my case) completely forget how we used to do this. So let's replace the real instrumentation test with a boring one that doesn't actually require all the boilerplate, but isn't harmed by it either. Depends on D147450 Differential Revision: https://phabricator.services.mozilla.com/D147451