There is an issue with kubectl apply and third party resources, so for
the time being we use create for TPRs, but apply for all manifests that
it can handle.

The $KUBECONFIG variable is like $PATH, and supports multiple files
separated by `:`, but --kubeconfig only takes a single file as a value.
Since kubectl picks up the $KUBECONFIG variable already, don't pass it
to kubectl.

Also, use --namespace instead of -n to support older kubectl versions.