win32: don't build a .msi package on arm64

It is not supported by the WIX 3.5 hardcoded in the MSI makefile.

There's arm64 support it WIX 3.14 but it's not release yet. We will also need to update our dockers and dotnet version which might be challenging. So for now we disable this type of package.

This will unbreak the nightly builds for arm64.

Sits on top of !2725 (merged).