[Zone Decommission]: Skip the drain timeout if the active request count is 0

[pranikum]

Is your feature request related to a problem? Please describe.
As per discussion #4586 (comment)
It better to skip the node drain timeout if the request count is already 0. Call node stats API 2 times before the node drain timeout starts after the weights are set and after the timeout ends.

Currently we are only doing when the timeout ends.

Describe the solution you'd like
We can add a call to node stats API before the timeout schedule begin and if count is 0. We can directly call the decommission process.

Describe alternatives you've considered
NA

Additional context
NA

[anasalkouz]

@pranikum are you going to work on this issue as well?