Add become to plays that delegate to localhost

'ansible_become' defined as a host_var or in the inventory for a host
has a higher precedence than 'become' defined within a playbook.

In change Id5b76a87809f03951c954fc3d752419a673403f7, 'become' was
defined explicitly for each play running against localhost. It will also
need to be defined in plays that delegate to localhost.

Change-Id: Ifb5e907594ca5fba459ee5a90b202e17db081f9a

test-install-neutron.yml

@@ -18,6 +18,7 @@
 - name: Make /lib/modules accessible on neutron_agent containers
   hosts: neutron_agent
   user: root
+  become: true
   gather_facts: true
   tasks:
     - name: Use the unconfined aa profile

test-setup-swifthosts.yml

@@ -16,6 +16,7 @@
 - name: Swift setup
   hosts: swift_hosts
   user: root
+  become: true
   gather_facts: true
   pre_tasks:
   - name: Ensure xfsprogs is installed on localhost (Ubuntu)