Use MSYS2 version where no full system upgrade is involved

Attempt to fix hangs like the following: https://gitlab.haskell.org/ghc/ghc/-/jobs/2187728

/---------------------------------------------------------------\
| Successfully built program 'ghc-bin' (Stage0 InTreeLibs).     |
| Executable: _build/stage0/bin/aarch64-unknown-mingw32-ghc.exe |
| Program synopsis: The Glorious Glasgow Haskell Compiler.      |
\---------------------------------------------------------------/
clang-19: error: unsupported option '-print-multi-os-directory'
clang-19: error: no input files
| Run Make "_build/stage1/libffi/build": none => none
hadrian/build-cabal --flavour=validate -j4 --broken-test= --bignum=native --docs=none test:all_deps reloc-binary-dist -V failed

Not sure what the actual reason