Support an upper bound when updating pods

[danielblando]

ZAU currently supports a maxUnavailable and ExponentialFactor params to set how fast we want to update our pods.

We can set maxUnavailable as int or exponential. But that could not be enough in some scenarios where pods scales.
Example: 30 pods running.
If we set the maxUnavailable as 3, when the number of pods grows this number will be obsolete and too small.
If we set the maxUnavailable as 10%, when the number of pods increase a lot (eg:2000), 200 maybe be too fast to update nodes.

It would be nice to have a upper bound limit to not allow the percentage to overcome a certain amount.
One idea is to have something similar to kubernets HPA where you can allow different policies and the behavior which they work
https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale/