add script to install ingress autoscaling

[qiliRedHat]

@paigerube14 PTAL

[qiliRedHat]

Test results

% ./install-ingress-autoscaling.sh 2
[INFO] ====Post Install Check====
[INFO] Getting hpa
NAME                      REFERENCE                   TARGETS     MINPODS   MAXPODS   REPLICAS   AGE
keda-hpa-ingress-scaler   IngressController/default   1/1 (avg)   1         2         2          9m55s
[INFO] Number of worker nodes: 2
[INFO] Ingresscontroller replicas: 2
[INFO] maxReplicaCount is 2. Replica number 2 equals to node number 2.

% ./install-ingress-autoscaling.sh omit
[INFO] ====Post Install Check====
[INFO] Getting hpa
NAME                      REFERENCE                   TARGETS     MINPODS   MAXPODS   REPLICAS   AGE
keda-hpa-ingress-scaler   IngressController/default   1/1 (avg)   1         100       2          10m
[INFO] Number of worker nodes: 2
[INFO] Ingresscontroller replicas: 2
[PASS] maxReplicaCount is omit. Replica number 2 equals to node number 2.

% ./install-ingress-autoscaling.sh 3
[INFO] ====Post Install Check====
[INFO] Getting hpa
NAME                      REFERENCE                   TARGETS     MINPODS   MAXPODS   REPLICAS   AGE
keda-hpa-ingress-scaler   IngressController/default   1/1 (avg)   1         3         2          2m49s
[INFO] Number of worker nodes: 2
[INFO] Ingresscontroller replicas: 2
[PASS] maxReplicaCount is 3. Replica number 2 equals to node number 2.

[qiliRedHat]

@paigerube14 PTAL

[paigerube14]

/lgtm

[qiliRedHat]

Merged after getting lgtm in peer review.