osds: do not set docker_exec_cmd fact

in `ceph-osd` there is no need to set `docker_exec_cmd` since the only
place where this fact is used is in `openstack_config.yml` which
delegate all docker command to a monitor node. It means we need the
`docker_exec_cmd` fact that has been set referring to `ceph-mon-*`
containers, this fact is already set earlier in `ceph-defaults`.

By the way, when collocating an OSD with a MON it fails because the container
`ceph-osd-{{ ansible_hostname }}` doesn't exist.

Removing this task will allow to collocate an OSD with a MON.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1584179

Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>
(cherry picked from commit 34e646e767)

roles/ceph-osd/tasks/main.yml

@@ -1,10 +1,4 @@
 ---
-- name: set_fact docker_exec_cmd
-  set_fact:
-    docker_exec_cmd: "docker exec ceph-osd-{{ ansible_hostname }}"
-  when:
-    - containerized_deployment
-
 - name: include check_mandatory_vars.yml
   include: check_mandatory_vars.yml