add retry handling for Combinator referenced selections

[ziaddevv]

Combinator currently treats missing or not ready referenced selections as retryable, because the dependency may still be materializing or could become available later.

We should add explicit logic maybe retry/re-trigger handling for these dependencies so CAN_RETRY has a real recovery path

[audiodude]

Honestly, users are very likely to be rapidly queueing builders, and they only take about a minute or two to materialize. This is a legitimate concern, but unlikely in practice.

I think the retryable exception should be handled by the UI if it happens after saving a Combinator.

If it happens during Combinator scheduled materialization, it can have retry logic like you suggest at the queued job level.