ceph-facts: move facts to defaults value

ceph-facts: move facts to defaults value

There's no need to define a variable via a fact if we can do it via a
default value. Using a fact could be interesseting to override the
default value on some condition.

- ceph_uid could be set to 167 by default because it's only different on
non containerized deployment on Debian/Ubuntu.
- rbd_client_directory_{owner,group,mode} could be set to ceph,ceph,0770
by default install of null as we are doing in the facts.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1875058
Signed-off-by: Dimitri Savineau <dsavinea@redhat.com>
(cherry picked from commit 7f997e623a7171fa6f00c43cd5b60f3882f8ed04)