Fix mysql-server install/upgrade on Ubuntu 16.04. (#39241)

* Fix mysql-server install/upgrade on Ubuntu 16.04.
* Prevent service restart in docker_secret test.

test/integration/targets/docker_secret/tasks/Ubuntu.yml

@@ -29,8 +29,29 @@
 - name: Add Docker repo
   shell: add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"  
 
-- name: Install Docker CE
+- block:
+    - name: Prevent service restart
+      copy:
+        content: exit 101
+        dest: /usr/sbin/policy-rc.d
+        backup: yes
+        mode: 0755
+      register: policy_rc_d
+
+    - name: Install Docker CE
       apt:
         name: docker-ce
         state: present
         update_cache: yes
+  always:
+    - name: Restore /usr/sbin/policy-rc.d (if needed)
+      command: mv {{ policy_rc_d.backup_file }} /usr/sbin/policy-rc.d
+      when:
+        - "'backup_file' in policy_rc_d"
+
+    - name: Remove /usr/sbin/policy-rc.d (if needed)
+      file:
+        path: /usr/sbin/policy-rc.d
+        state: absent
+      when:
+        - "'backup_file' not in policy_rc_d"

test/runner/setup/docker.sh

@@ -2,6 +2,9 @@
 
 set -eu
 
+# Required for newer mysql-server packages to install/upgrade on Ubuntu 16.04.
+rm -f /usr/sbin/policy-rc.d
+
 # Support images with only python3 installed.
 if [ ! -f /usr/bin/python ] && [ -f /usr/bin/python3 ]; then
     ln -s /usr/bin/python3 /usr/bin/python