Move non-K8s TestGrid config from k8s/test-infra to here

Some TestGrid configuration lives in https://github.com/kubernetes/test-infra, even though it should probably live all together here. We have a relatively easy way to add configuration from another instance (https://github.com/GoogleCloudPlatform/testgrid/tree/main/cmd/config_merger#configuration-list), but we need to make sure it's set up first and then begin migrating applicable configuration over.