Move .NET 8 Azure Linux 3.0 Images to main

Related to https://github.com/dotnet/dotnet-docker/issues/5331

When Azure Linux 3.0 is released, these images should be added to the main branch.

The Azure Linux Feature Roadmap is here: https://github.com/orgs/microsoft/projects/970/views/2

(Sprint assignment is tentative and doesn't represent any known release date)