src/test/fixtures/upgrades/processed-3.json doesn't seem to upgrade properly

I tried to load this fixture in the current version of the profiler: src/test/fixtures/upgrades/processed-3.json
I got the error `Error: Unable to find a global track from the given pid.`

Does that mean this fixture is incorrect (could be if we updated it manually) or that our upgrader is broken in some cases?

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-295)