Infinispan Operator should not use busybox in initcontainer

Currently, Infinispan Operator sets up an initContainer to fix possible permission issues on the storage used by the container. This initContainer uses busybox:latest :

https://github.com/infinispan/infinispan-operator/blob/master/pkg/controller/infinispan/infinispan_controller.go#L1270

This is a security issue. It can also create an exception if someone by mistake breaks the busybox shell.

It will be needed that an ubi8 image is used, like in the infinispan base image. Better if the same infinispan image (that also has a shell) can be used, so only one is downloaded.