MCM should always delete Node if corresponding Machine object is not present during termination flow

[elankath]

How to categorize this issue?

/area robustness
/kind bug
/priority 2

What happened:

There are cases where if a Machine is force-deleted, the Node cleanup does not occur. This happens if the Machine object is explicitly deleted by support. And the node lifecycle controller fails to clear the node.

How to reproduce it (as minimally and precisely as possible):

Difficult to reproduce. However, the Node object should be deleted ASAP after the corresponding Machine object is removed instead of needlessly waiting for node lifecycle controller.

Anything else we need to know?:

We should not skip node deletion in MCM if corresponding Machine object is missing. This was long known gap since we were depending upon clean-up by standard k8s controller.

This problem occurred in Azure.