[S58] O2.3: Update existing QA and regression test infrastructure for Fenix.
* [x] [Add support for Fenix into existing Tor Browser regression and integration tests](#34180)
* [ ] [Fix broken Fenix tests](https://gitlab.torproject.org/tpo/applications/fenix/-/issues/34181)
* [ ] [Write new integration tests for Tor Browser based on Fenix based on O1.2](https://gitlab.torproject.org/tpo/applications/tor-browser-bundle-testsuite/-/issues/34182)
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