Automatic merge from submit-queue (batch tested with PRs 45316, 45341)

Move hollow-node's initContainer from annotation to field

In 1.6, we have moved init containers spec from beta annotation to field. Updating this in kubemark hollow-node.

This should solve issues with setting of default fields (like ImagePullPolicy) in the container spec for older versions of apiservers too (as annotation->field change has been cherry picked for older releases too). We noticed this issue in https://github.com/kubernetes/kubernetes/issues/45290 where an old apiserver apparently wasn't setting default ImagePullPolicy for container spec inside annotations.

cc @wojtek-t @gmarek @gamename