[BEAM-12898] Minor fix to Kubernetes.groovy postBuildScript.
[BEAM-12898] Minor fix to Kubernetes.groovy postBuildScript.

apache/beam,apache/beam,robertwb/incubator-beam,lukecwik/incubator-beam,apache/beam,robertwb/incubator-beam,robertwb/incubator-beam,apache/beam,lukecwik/incubator-beam,lukecwik/incubator-beam,robertwb/incubator-beam,lukecwik/incubator-beam,apache/beam,apache/beam,chamikaramj/beam,robertwb/incubator-beam,robertwb/incubator-beam,apache/beam,robertwb/incubator-beam,chamikaramj/beam,chamikaramj/beam,robertwb/incubator-beam,apache/beam,chamikaramj/beam,lukecwik/incubator-beam,chamikaramj/beam,chamikaramj/beam,lukecwik/incubator-beam,apache/beam,apache/beam,chamikaramj/beam,chamikaramj/beam,lukecwik/incubator-beam,lukecwik/incubator-beam,chamikaramj/beam,apache/beam,robertwb/incubator-beam,lukecwik/incubator-beam,chamikaramj/beam,lukecwik/incubator-beam,robertwb/incubator-beam