Revert back to original Win CI install script

Since msys2/MSYS2-packages#2050 was fixed, we can now revert back to the
original install script.

Signed-off-by: Jakub Konka <kubkon@jakubkonka.com>

ci/azure/windows_msvc_install

@@ -4,12 +4,7 @@ set -x
 set -e
 
 pacman -Su --needed --noconfirm
-
-# Uncomment when https://github.com/msys2/MSYS2-packages/issues/2050 is fixed
-#pacman -S --needed --noconfirm wget p7zip python3-pip tar xz
-pacman -S --needed --noconfirm wget p7zip tar xz
-pacman -U --noconfirm http://repo.msys2.org/mingw/x86_64/mingw-w64-x86_64-python-3.8.4-1-any.pkg.tar.zst
-pacman -U --noconfirm http://repo.msys2.org/mingw/x86_64/mingw-w64-x86_64-python-pip-20.0.2-1-any.pkg.tar.xz
+pacman -S --needed --noconfirm wget p7zip python3-pip tar xz
 
 pip install s3cmd
 wget -nv "https://ziglang.org/deps/llvm%2bclang%2blld-10.0.0-x86_64-windows-msvc-release-mt.tar.xz"