Tests time out due to slow Setup Cpp setup

[dsharlet]

Intermittently, our tests are slow to run due to Setup Cpp taking a long time. When it's fast, it takes <1 minutes, when it's slow, it can take almost 10 minutes.

Some relevant background:

• Question: Can we cache the installation folders aminya/setup-cpp#212
• Publish docker images on Docker Hub aminya/setup-cpp#184

It seems like the setup is supposed to be cached on GH actions, but maybe it isn't sometimes?

Maybe using docker would fix this?

[dsharlet]

Looking at an example of this, I see this in the log:

Warning: Failed to add apt key via server keyserver.ubuntu.com: Error: Command failed with exit code 2: sudo 'gpg' '--no-default-keyring' '--keyring' 'gnupg-ring:/etc/apt/trusted.gpg.d/setup-cpp-ubuntu-archive.gpg' '--keyserver' 'keyserver.ubuntu.com' '--recv-keys' '3B4FE6ACC0B21F32'

Maybe this causes the cache to not work?

[dsharlet]

Hmm, there's another example that's slow, but does not have that failure in the log.

[dsharlet]

I think this will be fixed by #366. I thought we needed LLVM for asan or something else, but I guess not any more.