Move /etc/ssh/ssh_known_hosts bind mount where it's needed

There is no need to bind mount /etc/ssh/ssh_known_hosts for all the
containers. It's only useful for nova_compute and nova_libvirt
containers where live migration needs that file to work.

Change-Id: I9765dedf43d2c6765922eafaa9d5791ce488b41f

deployment/containers-common.yaml

@@ -147,9 +147,8 @@ outputs:
     value:
       list_concat:
         - *volumes_base
-        - - /etc/ssh/ssh_known_hosts:/etc/ssh/ssh_known_hosts:ro
-          # required for bootstrap_host_exec
-          - /etc/puppet:/etc/puppet:ro
+        # required for bootstrap_host_exec
+        - - /etc/puppet:/etc/puppet:ro
 
   pacemaker_restart_volumes:
     description: Common volumes for the pacemaker restart containers.

deployment/nova/nova-compute-container-puppet.yaml

@@ -808,6 +808,7 @@ outputs:
                     - {get_attr: [NovaLogging, volumes]}
                     - {get_param: NovaComputeOptVolumes}
                     -
+                      - /etc/ssh/ssh_known_hosts:/etc/ssh/ssh_known_hosts:ro
                       - /var/lib/kolla/config_files/nova_compute.json:/var/lib/kolla/config_files/config.json:ro
                       - /var/lib/config-data/puppet-generated/nova_libvirt:/var/lib/kolla/config_files/src:ro
                       - /etc/iscsi:/var/lib/kolla/config_files/src-iscsid:ro

deployment/nova/nova-libvirt-container-puppet.yaml

@@ -691,6 +691,7 @@ outputs:
                 - {get_attr: [ContainersCommon, volumes]}
                 - {get_attr: [NovaLibvirtLogging, volumes]}
                 -
+                  - /etc/ssh/ssh_known_hosts:/etc/ssh/ssh_known_hosts:ro
                   - /var/lib/kolla/config_files/nova_libvirt.json:/var/lib/kolla/config_files/config.json:ro
                   - /var/lib/config-data/puppet-generated/nova_libvirt:/var/lib/kolla/config_files/src:ro
                   - /etc/ceph:/var/lib/kolla/config_files/src-ceph:ro