Auto merge of #125546 - ChrisDenton:mingw-ci, r=Mark-Simulacrum

Try to not reinstall tools in mingw CI

Reinstalling the tools seems prone to failure (e.g. [latest](rust-lang/rust#125529 (comment))) and is more work. It also seems unnecessary as CI actually uses a vendored tarball for builds.

cc `@mati865`

Author: bors