Remove dependency from DockerHub for Kubernetes initContainers
Description
When setting FF_USE_LEGACY_KUBERNETES_EXECUTION_STRATEGY to false Kubernetes executor adds initContainer change-logs-permissions to runner's Pod in order to set permissions for the logs.
This initContainer has a hardcoded image busybox which is causing an issue for us with Docker Hub pulls quota introduced not long ago. Support for the custom image would enable us to use our private Docker registry instead.
Proposal
A simple solution would be adding configuration for initContainer image.