Elasticsearch misses genUUID field, resulting in missing Elasticsearch pods after RHOCP upgrade

Issue

• After RHOCP upgrade, Elasticsearch pods disappeared as genUUID field went missing in Elasticsearch custom resource (CR).

• Below logs are observed in Elasticsearch operator pod:

2021-03-12T13:54:05.637757911Z {"level":"error","ts":1615557245.637258,"logger":"kubebuilder.controller","msg":"Reconciler error","controller":"elasticsearch-controller","request":"openshift-logging/elasticsearch","error":"Failed to reconcile Elasticsearch deployment spec: Unsupported change to UUIDs made: Previously used GenUUID \"xxxxxxxx\" is no longer found in Spec.Nodes","stacktrace":"github.com/go-logr/zapr.(*zapLogger).Error\n\t/go/src/github.com/openshift/elasticsearch-operator/_output/src/github.com/go-logr/zapr/zapr.go:128\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem\n\t/go/src/github.com/openshift/elasticsearch-operator/_output/src/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:217\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func1\n\t/go/src/github.com/openshift/elasticsearch-operator/_output/src/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:158\nk8s.io/apimachinery/pkg/util/wait.JitterUntil.func1\n\t/go/src/github.com/openshift/elasticsearch-operator/_output/src/k8s.io/apimachinery/pkg/util/wait/wait.go:133\nk8s.io/apimachinery/pkg/util/wait.JitterUntil\n\t/go/src/github.com/openshift/elasticsearch-operator/_output/src/k8s.io/apimachinery/pkg/util/wait/wait.go:134\nk8s.io/apimachinery/pkg/util/wait.Until\n\t/go/src/github.com/openshift/elasticsearch-operator/_output/src/k8s.io/apimachinery/pkg/util/wait/wait.go:88"}