Libbeat: add_kubernetes_metadata is missing field declaration for kubernetes.replicaset

[alakahakai]

Libbeat: add_kubernetes_metadata is missing field declaration for kubernetes.replicaset, which causes test exception as follows:
raise Exception("Key '{}' found in event is not documented!".format(key))
Exception: Key 'kubernetes.replicaset.name' found in event is not documented!

[alakahakai]

Addressed in {pull}11134[11134]