Auto merge of #115029 - ehuss:remove-apple-alt, r=Mark-Simulacrum

Remove apple-alt dist build.

This removes the dist-x86_64-apple-alt build to reduce CI usage because I suspect nobody is using it. This builder is almost identical to the `dist-x86_64-apple` with the small difference that the latter adds `rust.lto=thin`, and I do not think that difference was intentional. The reason they are identical is because llvm assertions were disabled in #44610, but I did not see any discussion about the consequence that this made the alt build identical to the normal build. Perhaps because #44610 was intended to be temporary?

Author: bors