Faster CI runners

[LegNeato]

Previously Embark used paid runners to get faster builds. As part of the transition we went to the slower Github action runners. We should look into getting credits and/or sponsors for faster CI if it is a problem.

This is what they used to have:

          - os: ubuntu-20.04-16core
            target: x86_64-unknown-linux-gnu
          - os: windows-2022-16core
            target: x86_64-pc-windows-msvc
          - os: macOS-latest-xl
            target: x86_64-apple-darwin
          - os: ubuntu-20.04-16core
            target: aarch64-linux-android
            host: x86_64-unknown-linux-gnu

[rydb]

I ran the CI locally on Friday for the Ubuntu targets, and my initial thoughts:

1. dependencies seem to be duplicating.

sudo act --verbose

shows me the "installing depenendency" steps running 4 times for different tests. I think we need to fix CI to share the same ubuntu container to stop duplication. I'm looking into this.

2. we should switch out Embark's CI runners for something leaner since this is its own project now.