Use CONTAINER_TOOL in all calls, directory in kubectl apply

[fabianofranz]

A couple minor fixes:

• Use CONTAINER_TOOL where docker was hardcoded in the Makefile; and
• kubectl apply -k must point to a directory where kustomization.yaml exists.

[fabianofranz]

@acornett21 @bcrochet ptal

[acornett21]

@fabianofranz Thanks for pointing this out. I think the intent was the -f flag, but -k makes sense in case in the future someone wants to add kustomizations.

[fabianofranz]

I think the intent was the -f flag, but -k makes sense in case in the future someone wants to add kustomizations.

Sounds good. Since a kustomization.yaml exists, this will work now already and in future if kustomizations are added.