Set IsPackable to true for the k8s project on non rtw builds

[benjaminpetit]

Fix #2134

This will enable the package creation only for non rtw build, meaning that the NuGet will be created for nightly and preview builds.

[MihaZupan]

I believe we wanted to re-enable only the nightly-build part that goes to the separate feed.
If we're shipping a preview version of YARP to NuGet, we don't want to also ship a preview of the k8s package. I don't know how we would go about disabling the publishing of this package only for the NuGet publishing though.

Ideally, we would find a way to do so without having to re-disable and re-enable this flag every time we publish a preview, but maybe that's an okay compromise given we don't release all that often.

[benjaminpetit]

Then the only solution is to modify the powershell script that publishes the nuget to explicitly ignore this package (or even better, only publish a certain list of packages).

Any reason to not ship this package as a preview in the official nuget feed?

[Tratcher]

Any reason to not ship this package as a preview in the official nuget feed?

We wouldn't want to ship an RC version for example.

Suggestion:

• Make it always packable
• Mark it as non-shipping
• Update the release script to pull from '_microsoft-reverse-proxy-official\artifacts\release\shipping' (excluding symbol packages) instead of '_microsoft-reverse-proxy-official\PackageArtifacts'