Don't migrate storage version if CRD has one storage version #2155

Job	Run time
Unit Test (knative/serving)	9m 24s
Unit Test (knative/networking)	9m 47s
Unit Test (knative/eventing)	20m 54s
Unit Test (knative/operator)	12m 35s
Unit Test (knative/client)	11m 35s
Unit Test (knative-extensions/eventing-autoscaler-keda)	10m 12s
Unit Test (knative-extensions/eventing-ceph)	7m 52s
Unit Test (knative-extensions/eventing-github)	10m 42s
Unit Test (knative-extensions/eventing-gitlab)	10m 13s
Unit Test (knative-extensions/eventing-kafka)	11m 2s
Unit Test (knative-extensions/eventing-kafka-broker)	19m 37s
Unit Test (knative-extensions/eventing-rabbitmq)	19m 46s
Unit Test (knative-extensions/eventing-redis)	11m 10s
Unit Test (knative-extensions/kn-plugin-admin)	7m 17s
Unit Test (knative-extensions/net-certmanager)	7m 47s
Unit Test (knative-extensions/net-contour)	7m 14s
Unit Test (knative-extensions/net-http01)	6m 33s
Unit Test (knative-extensions/net-istio)	11m 58s
Unit Test (knative-extensions/net-kourier)	8m 26s
	3h 34m 4s

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