AOT'd Windows Containers should use windows images instead of dotnet/runtime-deps

[baronfel]

There's no windows version of dotnet/runtime-deps - self-contained applications targeting windows should use one of

• mcr.microsoft.com/windows/nanoserver
• mcr.microsoft.com/windows/servercore

with appropriate tags.

Keeping in line with #414 we should bias towards servercore here, as users can always override that decision.

[baronfel]

Removing the prority: high label because users are never inferred to use the windows variants of images anymore.

[baronfel]

Closing as users have to manually select images when using Windows RIDs.