opendatahub: Create OCP 4.20 cluster pool (#77557)

Add new opendatahub-ocp-4-20-amd64-aws cluster pool to resolve 4.19 cert rotation regression causing ServiceAccount controller failures.

Pool configuration:
- Version: 4.20 (imageSet: ocp-release-4.20.17-multi)
- Size: 12 clusters, maxSize: 40, runningCount: 2
- Region: us-east-1 (AWS)
- Hibernation resume timeout: 20m

This creates the pool but does not switch CI jobs to use it yet. A follow-up
PR will update ci-operator config to use version 4.20 after the pool is ready.

Co-authored-by: Dayakar Maruboena <dmaruboe@dmaruboe-thinkpadp1gen7.rht.csb>

Author: dayakar349

clusters/hosted-mgmt/hive/pools/opendatahub/opendatahub-ocp-4-20-amd64-aws_clusterpool.yaml

@@ -0,0 +1,42 @@
+apiVersion: hive.openshift.io/v1
+kind: ClusterPool
+metadata:
+  creationTimestamp: null
+  labels:
+    architecture: amd64
+    cloud: aws
+    owner: opendatahub
+    product: ocp
+    region: us-east-1
+    version: "4.20"
+    version_lower: 4.20.0-0
+    version_stream: 4-stable
+    version_upper: 4.21.0-0
+  name: opendatahub-ocp-4-20-amd64-aws
+  namespace: opendatahub-cluster-pool
+spec:
+  baseDomain: openshift-ci-aws.rhaiseng.com
+  hibernationConfig:
+    resumeTimeout: 20m0s
+  imageSetRef:
+    name: ocp-release-4.20.17-multi-for-4.20.0-0-to-4.21.0-0
+  installAttemptsLimit: 1
+  installConfigSecretTemplateRef:
+    name: opendatahub-install-config-aws
+  labels:
+    tp.openshift.io/owner: opendatahub
+  maxSize: 40
+  platform:
+    aws:
+      credentialsSecretRef:
+        name: opendatahub-aws-credentials
+      region: us-east-1
+  pullSecretRef:
+    name: pull-secret
+  runningCount: 2
+  size: 12
+  skipMachinePools: true
+status:
+  ready: 0
+  size: 0
+  standby: 0