Revert "feat(infra.ci/agent): new cluster in azure sponsored for infra.ci agents"

[smerle33]

Reverts #715

Error: creating Kubernetes Cluster (Subscription: "<redacted>"
17:43:25  │ Resource Group Name: "infra-ci-jenkins-io-kubernetes-agents"
17:43:25  │ Kubernetes Cluster Name: "infracijenkinsio-agents-1"): performing CreateOrUpdate: unexpected status 400 (400 Bad Request) with response: {
17:43:25  │   "code": "SubnetNotAssociatedWithNATGateway",
17:43:25  │   "details": null,
17:43:25  │   "message": "Subnet '/subscriptions/<redacted>/resourceGroups/infra-ci-jenkins-io-sponsorship/providers/Microsoft.Network/virtualNetworks/infra-ci-jenkins-io-sponsorship-vnet/subnets/infra-ci-jenkins-io-sponsorship-vnet-infraci_jenkins_io_kubernetes-agent' must have a NAT gateway associated for outbound connection.",
17:43:25  │   "subcode": ""
17:43:25  │  }

[dduportal]

no need to revert: fix should be quick (in https://github.com/jenkins-infra/azure-net/blob/69451c264a98b2e96f89022ffe321d6ea1fd27f5/gateways.tf#L102-L118)

[dduportal]

Issue fixed by jenkins-infra/azure-net#250: I'll retry the main branch build to create the cluster, or I'll merge this PR to have a successful build until tomorrow

[dduportal]

New error: see #715 (comment)

[dduportal]

19:15:24  
azurerm_kubernetes_cluster.infracijenkinsio_agents_1: Creation complete after 8m38s [id=/subscriptions/1311c09f-aee0-4d6c-99a4-392c2b543204/resourceGroups/infra-ci-jenkins-io-kubernetes-agents/providers/Microsoft.ContainerService/managedClusters/infracijenkinsio-agents-1]