Followup from #40091 and tor-browser-build#40073: we should try to bundle the builtin https-everywhere extension entirely in tor-browser and avoid the parts in tor-browser-build. I tried this with a `Makefile.in` that unzipped the xpi into `dist/fennec/assets/extensions/https-everywhere`, but there was some unexpected behaviour, see https://gitlab.torproject.org/tpo/applications/tor-browser/-/merge_requests/42#note_2708014. We should investigate and fix this.