tasks: horizon_post_install: Add missing become statements for horizon user

The operation needs to be performed as the horizon user since our user
may or may not have access to the horizon directory.

Change-Id: I2fb11b6874256ef3ee26e1e255cb25c3087fbc07

tasks/horizon_post_install.yml

@@ -90,6 +90,8 @@
 
 - name: Compile messages for translation
   command: "{{ horizon_bin }}/horizon-manage.py compilemessages"
+  become: yes
+  become_user: "{{ horizon_system_user_name }}"
   args:
     chdir: "{{ horizon_lib_dir }}/{{ item }}"
   changed_when: false

tasks/main.yml

@@ -72,6 +72,8 @@
 - name: Ensure messages are compiled for translation
   async_status:
     jid: "{{ item.ansible_job_id }}"
+  become: yes
+  become_user: "{{ horizon_system_user_name }}"
   register: async_compile_messages_check
   until: async_compile_messages_check.finished
   retries: 300