Fix nova-libvirt's secrets - device or resource is busy

This patch removes the nova_libvirt_secret container volume because
it is a complete antipattern, and during testing, I found that
it causes problems. When it was necessary to copy libvirt secrets
from /etc/kolla/nova-libvirt/secrets, the container logs reported that
the resource is busy - precisely because it was a mounted container
volume. This, of course, is unnecessary because the secrets are copied
to the kolla host in /etc/kolla/nova-libvirt/secrets.

Closes-Bug: #2073678
Change-Id: I715a6a95f9d32d62a8199727ddbaddd0dd7baa2d

ansible/roles/nova-cell/defaults/main.yml

@@ -380,7 +380,6 @@ nova_libvirt_default_volumes:
   - "{{ nova_instance_datadir_volume }}:/var/lib/nova/"
   - "{% if enable_shared_var_lib_nova_mnt | bool %}/var/lib/nova/mnt:/var/lib/nova/mnt:shared{% endif %}"
   - "nova_libvirt_qemu:/etc/libvirt/qemu"
-  - "nova_libvirt_secrets:/etc/libvirt/secrets"
   - "{{ kolla_dev_repos_directory ~ '/nova/nova:/var/lib/kolla/venv/lib/python' ~ distro_python_version ~ '/site-packages/nova' if nova_dev_mode | bool else '' }}"
 nova_ssh_default_volumes:
   - "{{ node_config_directory }}/nova-ssh/:{{ container_config_directory }}/:ro"

ansible/roles/nova-cell/tasks/deploy.yml

@@ -35,3 +35,5 @@
     # and there is a cell conductor in the inventory to delegate to.
     - all_computes_in_batch | length > 0
     - groups[nova_cell_conductor_group] | length > 0
+
+- import_tasks: post-config.yml

ansible/roles/nova-cell/tasks/post-config.yml

@@ -0,0 +1,8 @@
+---
+# TODO(kevko) Remove in E cycle
+- name: Remove old nova_libvirt_secrets container volume
+  become: true
+  kolla_container:
+    container_engine: "{{ kolla_container_engine }}"
+    action: "remove_volume"
+    name: nova_libvirt_secrets

ansible/roles/nova-cell/tasks/rolling_upgrade.yml

@@ -14,3 +14,5 @@
 
 - name: Flush handlers
   meta: flush_handlers
+
+- import_tasks: post-config.yml

releasenotes/notes/bug-2073678-45f31547395ef3c7.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Fixes busy libvirt's secret volume while secrets are changing.
+    `LP#2073678 <https://launchpad.net/bugs/2073678>`__