Update public pool names

[MattGal]

This change is required to continue building PRs in the dotnet public repo. The agents and images used in the new project / organization are identical and build regressions are not expected. Updating files under eng/common is intentional to move as much as possible over to viable build agents (normally this is not done).

For questions / concerns, please stop by the .NET Core Engineering Services First Responders Teams Channel.