Update linter config and address lint warnings/failures #2419

Job	Run time
Unit Test (knative/serving)	9m 43s
Unit Test (knative/networking)	3m 58s
Unit Test (knative/eventing)	13m 22s
Unit Test (knative/operator)	6m 35s
Unit Test (knative/client)	7m 5s
Unit Test (knative-extensions/eventing-autoscaler-keda)	5m 14s
Unit Test (knative-extensions/eventing-ceph)	4m 58s
Unit Test (knative-extensions/eventing-github)	5m 33s
Unit Test (knative-extensions/eventing-gitlab)	5m 10s
Unit Test (knative-extensions/eventing-kafka-broker)	11m 9s
Unit Test (knative-extensions/eventing-rabbitmq)	10m 39s
Unit Test (knative-extensions/eventing-redis)	5m 39s
Unit Test (knative-extensions/kn-plugin-admin)	4m 29s
Unit Test (knative-extensions/net-certmanager)	4m 13s
Unit Test (knative-extensions/net-contour)	4m 26s
Unit Test (knative-extensions/net-istio)	6m 8s
Unit Test (knative-extensions/net-kourier)	4m 36s
	1h 52m 57s

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