Fix: pdb-min-available when Replica number is controlled via HPA

[jpedrobf]

I believe this solves #637.

The commit history might be a little messy but it was made with heart 💚

[jpedrobf]

@janisz, giving an update: @jvtartaglia helped a lot in refining the code to avoid nested for inside the code and reduce complexity. If there's any other feedback, we're happy to follow up on it 😄

[janisz]

LGTM except one last comment about supported versions.
Also if you like it will be great to have a e2e test for that with different autoscaling version .e.g: that will pass on this PR

---
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: baz
  namespace: bar
spec:
  minAvailable: 1
  selector:
    matchLabels:
      name: example
---
apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
  name: app
  namespace: bar
spec:
  minReplicas: 4
  maxReplicas: 100
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: foo
    namespace: bar
  targetCPUUtilizationPercentage: 85
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: foo
  namespace: bar
spec:
  selector:
    matchLabels:
      name: example
  template:
    metadata:
      labels:
        name: example

[janisz]

@jpedrobf Thank you!