- `ubuntu-22.04-firezone` is a 16-core builder for ~~kotlin~~ and docker
- ~~`macos-13-xlarge` is an M1 builder for Apple and docker arm64~~
- Configure the Gradle build cache
- Upgrade kotlin plugins, Android minSDK to 30, and gradle to 8.4
Edit: It appears that even using the largest runners for kotin and swift
don't speed the builds up that much (~30%), but will substantially
increase our cost, so I've reverted them to free.
Fixes#2210