makefile: use ceph based containers by default
DOCKER_CI_IMAGE = go-ceph-ci
CONTAINER_CMD := docker
CONTAINER_OPTS := --security-opt $(shell grep -q selinux /sys/kernel/security/lsm && echo "label=disabled" || echo "apparmor:unconfined")
-CONTAINER_CONFIG_DIR := .
+CONTAINER_CONFIG_DIR := testing/containers/ceph
VOLUME_FLAGS :=
CEPH_VERSION := nautilus
