Mono legs for non-1xx feature bands

[mthalman]

There's an issue with running Mono legs in non-1xx feature bands due to the lack of published SB artifacts for Mono: https://github.com/dotnet/dotnet/blob/5088919af0e4a144ce5b294542f472bf668c9cc8/eng/pipelines/templates/stages/source-build-and-validate.yml#L109

Because there is no publishing of Mono artifacts, and that there's no logic to attempt to consume one, a build leg in a non-1xx branch will get the non-Mono version of the artifacts that was produced by the same distro/architecture. This will subsequently fail in the scenario tests when attempting to run the VerifyWebTemplatePublishBundledAot test which should be skipping in the context of Mono but does not because it is detected to not be a Mono runtime.

In summary, the Mono legs that currently run in non-1xx feature bands are not actually making use of a Mono runtime. This is a testing gap.

[mthalman]

At this time there doesn't seem to be any requirement from distros that need 2xx+ features to have Mono support. Closing this as won't fix. We can re-open if requirements change.