Add retries to install packages required for Neutron

Jobs sometimes fail and timeout on this task so adding retries
to make it less prone to CI failures.

Change-Id: I4ecad7ecf56962fc272989a8fafc66b0ff1e5185

test-install-neutron.yml

@@ -77,6 +77,10 @@
       package:
         name: "{{ required_packages[ansible_pkg_mgr] }}"
         state: present
+      register: install_packages
+      until: install_packages is success
+      retries: 5
+      delay: 2
 
     - include: ensure-rabbitmq.yml
       vhost_name: "{{ neutron_rabbitmq_vhost }}"