Do not create cinder backup pool and key when cephadm is used

When cephadm is used, if ENABLE_CEPH_C_BAK is True both pool and
key are created by devstack-plugin-ceph. This piece of code can
still stay here to make sure the cinder config is properly built.

Change-Id: I799521f008123b8e42b2021c1c11d374b834bec3
1 file changed