Implement timeout for instance drain

[alanbover]

Currently when an instance is marked to be deleted, is tagged with value=timestamp.
We might want to wait a certain time for the node to be drained, but depending on the situation this might never happen (or might take a really long time).

For that scenario, we want to wait a certain time for the instance to be drained. If after this time the instance still has tasks from protected frameworks, we should kill the instance anyway.