Fix sidekiq kubeconfig to reflect the correct node labels

Issue: gitlab-com/gl-infra/delivery#2243 (closed) as part of epic: gitlab-com/gl-infra&687 (closed) and the actual label change on the nodes are in this MR: https://ops.gitlab.net/gitlab-com/gl-infra/config-mgmt/-/merge_requests/3979

This MR covers the TODO to set the nodeSelector to type: 'sidekiq' as that's what we changed the node labels to in the above MR.