Transition published containers, and Terraform code, to deploy ARM containers instead

[alexdlaird]

Cheaper and faster.

[alexdlaird]

This may not be realistic until GitHub finally makes its ARM GitHub Action runners available for open source projects. Without that, switching to emulated multi-platform arm64 builds is incredibly slow (making builds go from 2 minutes to 20, 30, and 50 minutes in some cases).

[alexdlaird]

GitHub is now testing out ARM runners. They work great for the builds, but do not yet have the Chrome WebDriver pre-installed on them. As a result, when running the CI tests (as part of the deployment), we have to mix-and-match architectures (read: emulation) which becomes incredibly slow. Tried several workarounds for this, none of them great, so continuing to use the AMD runners to publish x86 images for now.

When we are ready to change this up, all that needs to happen is runs-on changes to an ARM runner, and PLATFORM is removed from the env: section of build-release.yml. There should also be a change to tag names that are published to include an -arm suffice, so it's clear when we transition for historic images.