agent_servers: Use correct default settings (#51136)

These are edge cases, but there are a few ways you can get into a state
where you are setting favorites for registry agents and we don't have
the setting yet. This prioritizes `type: registry` for agents that we
have in the registry, especially the previous built-ins.

Release Notes:

- N/A
a99366a940Ben Brandt committed on 3/9/2026, 10:41:59 PM· committed by GitHubparent4e9e944
2 files changedLine totals unavailable