Ensure that facts are gathered for newly created containers

If this is not done before the systemd_service role is run then
the operating system specific variables file cannot be loaded
and the container creation will fail with:

TASK [systemd_networkd : Gather variables for each operating system] ***********
fatal: [container1]: FAILED! => {"msg": "No file was found when using first_found.

This is due to varaibles like ansible_distribution being unset
until facts gathering has been done, and the lack of facts gathering
is probably exposed by the recent upgrade to ansible 2.9.

Depends-On: https://review.opendev.org/728995
Depends-On: https://review.opendev.org/728997
Change-Id: Ifee09ed58e32584d799fca13f33f842765f9cfb9

tasks/main.yml

@@ -347,6 +347,10 @@
   tags:
     - skip_ansible_lint
 
+- name: Gather facts for containers
+  setup:
+    gather_subset: "network,hardware,virtual"
+
 # This point the container is running. Delegation should no longer be required.
 # ==============================================================================
 - name: Run the systemd-networkd role