Fix potential `--kubeconfig` redefined error #2126

Job	Run time
Unit Test (knative/serving)	14m 25s
Unit Test (knative/networking)	8m 10s
Unit Test (knative/eventing)	20m 45s
Unit Test (knative/operator)	11m 1s
Unit Test (knative/client)	13m 0s
Unit Test (knative-extensions/eventing-autoscaler-keda)	7m 52s
Unit Test (knative-extensions/eventing-ceph)	8m 44s
Unit Test (knative-extensions/eventing-github)	10m 26s
Unit Test (knative-extensions/eventing-gitlab)	8m 47s
Unit Test (knative-extensions/eventing-kafka)	11m 36s
Unit Test (knative-extensions/eventing-kafka-broker)	18m 51s
Unit Test (knative-extensions/eventing-rabbitmq)	14m 30s
Unit Test (knative-extensions/eventing-redis)	9m 27s
Unit Test (knative-extensions/kn-plugin-admin)	7m 29s
Unit Test (knative-extensions/net-certmanager)	7m 12s
Unit Test (knative-extensions/net-contour)	7m 52s
Unit Test (knative-extensions/net-http01)	7m 29s
Unit Test (knative-extensions/net-istio)	9m 31s
Unit Test (knative-extensions/net-kourier)	7m 34s
	3h 24m 41s

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