Looking in the source code it's clear that there's a build runner that is supposed to be running the rustls tests, however, it's difficult to actually find that build because it's not linked in Github's checks UI. Further the fact that Github checks reports ~45 different tests made me think that I just wasn't looking hard enough and it must be there somewhere.

It turns out there is a whole other builder suite at https://curl.zuul.vexxhost.dev/builds?job_name=curl-debug-rustls (and maybe others?) that is running CI tests. While there are issues with that builder (#7522) we could probably do a better job of documenting the different CI jobs that are running currently.

I propose adding tests/CI.md with documentation on:

• The different locations that CI checks are run
• Which location runs which subset of tests
• Where you should look to verify your PR did not introduce regressions
• Who owns keys or knows how to set up CI (maybe the answer is just @bagder)

I'd also like to add a link in zuul.d/jobs.yaml with a link to the curl.zuul.vexxhost.dev page, just to make that link more explicit.

I would be happy to take a first stab at this.