In JDK-8256983 we updated the OS and compilers used for GitHub actions to use a specific OS version and compiler version for each platform. This is to both better insulate ourselves from changes to the defaults on the GitHub actions servers, and also to more closely match the build environment of our CI builds.

We intentionally didn't specify the specific version of Visual Studio 2019 on Windows for two reasons. First, it required a follow-on fix that wasn't implemented at that time (JDK-8255713, which has since been implemented). Second, it is more complicated and increases the build time significantly to download and install a specific version. If we do this, we would need some sort of caching.