Better checking of current scale events in progress before scaling up/down

[naorlivne]

Expected/Wanted Behavior

If a scaling event is already in progress (was increased/decreased) but the server has not yet fully joined/left the cluster another server shouldn't be added/removed

Actual Behavior

the current scaling events doesn't cover all edge cases so a server might be added while another server is in the process of being added

This can be achieved by comparing the number of servers in the spotinst API to the kubernetes API and if the 2 don't match wait until they do