bump go.mod go version to 1.22 and drop unused dependency #2408

Job	Run time
Unit Test (knative/serving)	9m 51s
Unit Test (knative/networking)	3m 56s
Unit Test (knative/eventing)	13m 20s
Unit Test (knative/operator)	7m 4s
Unit Test (knative/client)	7m 23s
Unit Test (knative-extensions/eventing-autoscaler-keda)	4m 47s
Unit Test (knative-extensions/eventing-ceph)	55s
Unit Test (knative-extensions/eventing-github)	5m 59s
Unit Test (knative-extensions/eventing-gitlab)	5m 26s
Unit Test (knative-extensions/eventing-kafka-broker)	54s
Unit Test (knative-extensions/eventing-rabbitmq)	54s
Unit Test (knative-extensions/eventing-redis)	5m 52s
Unit Test (knative-extensions/kn-plugin-admin)	4m 30s
Unit Test (knative-extensions/net-certmanager)	4m 18s
Unit Test (knative-extensions/net-contour)	4m 43s
Unit Test (knative-extensions/net-istio)	6m 2s
Unit Test (knative-extensions/net-kourier)	4m 30s
	1h 30m 24s

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