This exposes the proper v1beta3 API endpoint when the user specifies
the --runtime_config=api/v1beta3 argument to the apiserver. v1beta3
is still considered experimental and subject to change.
--runtime_config is a map of string keys and values, that can be
specified by providing
--runtime_config=a=b,b=c,d,e
Only the key must be specified, the value can be omitted.
Enables v1beta3 in hack/local-up-cluster.sh and hack/test-cmd.sh
