Condition update and Event when SkipDrain are Completed/DrainSucceeded

[dbenque]

If skipDrain flag is set the Drain activity is not performed and returns no error:
https://github.com/planetlabs/draino/blob/master/internal/kubernetes/drainer.go#L262

As a consequence the Drain activity that was schedule thinks that the Drain was successfully performed :
https://github.com/planetlabs/draino/blob/master/internal/kubernetes/drainSchedule.go#L129

and the condition is updated with Completed and an event is fired with DrainSucceeded:
https://github.com/planetlabs/draino/blob/master/internal/kubernetes/drainSchedule.go#L151-L154

What can be done:

• Either (A) take into account the skipDrain at schedule time and just don't mark the node and don't plan any schedule
• Or (B) return a specific error from drainer.Drain and check against this error to update the condition with Skipped instead of Completed and send a different type of event DrainSkipped

(B) is more code but a bit more verbose for the user, so I would be in favor of (B).

I can do the fix, what solution do you prefer?