Drop Kubernetes extension from requirements #4
Description
Idea:
It would be best to have only GCP related activities in that extension.
Hence we could remove all chaosk8s functions call from this extension, and then removes the chaostoolkit-kubernetesextension from the requirements.txt
Impact:
This would imply to deprecate the swap_node_pool function, because it uses the drain_nodes function from the chaosk8s package. This call shall be defined as an activity in the experiment (rather than being embedded in another extension)