* We don't need to check out the js-sdk separately anymore
* Remove the vite proxying: there's no need since Matrix HSes allow
cross origin requests. This will let us move the default homeserver
config to the config file (in a separate PR...)
* Remove the product name variable which just set it to the default anyway
This build script might change more soon (we shouldn't really need
to checkout & link the js-sdk at all) but for now let's just switch
the branch now group-call is merged.