Add retries to apt update in cache proxy task
Add retries to apt update in cache proxy task

When apt update was added to the package-cache-proxy.yml task,
the retries and delay fields were omitted.

Change-Id: I8e86b524269e3bf4ba2b5889d51ebf64d86472c8

robb-romans/openstack-ansible,cloudnull/os-ansible-deployment,BjoernT/openstack-ansible,cfarquhar/openstack-ansible,BjoernT/os-ansible-deployment,yanyao/openstack-ansible,BjoernT/openstack-ansible,os-cloud/os-ansible-deployment,BjoernT/os-ansible-deployment,yanyao/openstack-ansible,weezer/openstack-ansible,robb-romans/openstack-ansible,cfarquhar/openstack-ansible,bunchc/openstack-ansible,stackforge/os-ansible-deployment,stackforge/os-ansible-deployment,BjoernT/os-ansible-deployment,os-cloud/os-ansible-deployment,openstack/openstack-ansible,cloudnull/os-ansible-deployment,weezer/openstack-ansible,openstack/openstack-ansible,bunchc/openstack-ansible