[WASI] re-enable pre installed WASI SDK & wasmtime

[pavelsavara]

or use nuget with https://github.com/dotnet/wasi-sdk
it was disabled for version upgrade

See #101392

[dotnet-policy-service]

Tagging subscribers to 'arch-wasm': @lewing
See info in area-owners.md if you want to be subscribed.