Gather build hosts facts once.

In [1] the build host facts gathering was moved from a place in the
code which was covered by run_once to one that is not. The task is
now missing a run_once so it iterates over the repo_all group for
each host in the play which could be a very large number of tasks.

[1]  I79a10a3f774246ab9c57313f19f3804f9422e08c

Change-Id: Ic86c19ca48fb55ad2c464c22f31ac41c5cc4c2e5

tasks/main.yml

@@ -37,6 +37,7 @@
   with_items: "{{ groups['repo_all'] | default([inventory_hostname]) }}"
   tags:
     - always
+  run_once: true
 
 # NOTE(noonedeadpunk): If you are deploying services from local forks high load on which is not
 #                      an issue for you, you can disable this with `venv_wheel_build_skip_check: true`