get rid of the StatusChecker component

[ndr-brt]

Feature Request

StatusChecker was a component that took care of checking the transfer completion in the TransferProcess state machine.
It's completely useless now because:

• in a "provider push" scenario the data-plane already takes care of notifying the control-plane when a transfer has been completed
• in a "consumer pull"/"streaming" scenario, the upcoming policy monitor will take care of evaluating the policy and eventually complete the transfer.

So the StatusChecker can be removed as a whole, and free some state machine cycles.

Which Areas Would Be Affected?

transfer process

Why Is the Feature Desired?

cleanup