Auto merge of #136588 - ChrisDenton:no-msys2, r=Kobzol

Don't install msys2 in CI

windows-msvc doesn't need it and windows-gnu [installs its own version](https://github.com/rust-lang/rust/blob/master/src/ci/scripts/install-mingw.sh)

try-job: dist-x86_64-msvc
try-job: dist-i686-msvc
try-job: dist-aarch64-msvc
try-job: dist-i686-mingw
try-job: dist-x86_64-mingw
try-job: dist-x86_64-msvc-alt

Author: bors