tests: docker images must use install-deps.sh

tests: docker images must use install-deps.sh

The dockerfiles must run install-deps.sh instead of duplicating the
package list that is found in ceph.spec.in and debian/control.

A directory is created for each os_type and provided as a context for
docker build to use. The former $os_type.dockerfile is moved into
$os_type/Dockerfile.in (the .in as a reminder that it will be variable
substituted).

http://tracker.ceph.com/issues/10401 Fixes: #10401

Signed-off-by: Loic Dachary <ldachary@redhat.com>