envoyproxy
android/ci: run CI jobs on Linux
Make all Android CI jobs use Linux as opposed to the combination of both Linux and macOS.
Currently some of the Android CI jobs are ran on Linux (android_tests / kotlin_tests_linux) while the other are ran on macOS (android_tests / kotlin_tests_mac, android_tests / java_tests_mac, android_build / kotlin_helloworld).
Building Envoy Mobile aar and running example apps in Android emulator requires a full Android toolchain - that's something that may need to be set up on our Linux machines before we are able to migrate over to them.
@Augustyniak let us know (Engflow) when you'll start this work to make sure everything works on the remote execution end :)
cc @Yannic
One way to do this would be to add Android toolchain stuff (and possible Android Studio stuff?) to https://github.com/envoyproxy/envoy-build-tools which is the repo that generates the Docker image we use to run Android CI jobs, both on the GitHub Actions hosts and the Engflow remote executors.
