Update Polling Termination Logic to use finished_processing attribute

[KPreisner]

What?

Modify existing polling termination conditionals to use the new finished_processing attribute: https://sindri.app/docs/reference/api/circuit-detail/#:~:text=JobStatus%20choices-,finished_processing,-Finished%20Processing%20(boolean)

Why?

With the Sindri release v1.14.5, the Circuit/Proof status/detail API endpoint response objects now have the new boolean attribute finished_processing, which the API derives from the status DB field of those objects.

Sindri added this new attribute to their Circuit/Proof record API response schemas to further the separation of concerns from backend to frontend coding details. This allows Sindri clients to know when a Circuit/Proof record is "finished" without needing to know what all of the possible combinations of attributes determine an in-progress vs finished object.