base: Move log-inventory to localhost

This role is delegated to localhost and set to run_once, so it's
safe to run everywhere, however, if we use it that way, we don't
run it on nodeless jobs.  Instead, explicitly run it on localhost
so that it does run once in *all* cases.

Change-Id: Ifde08514047903b2679f5f57e5ef93c4b57274e3

playbooks/base/pre.yaml

@@ -2,6 +2,7 @@
   roles:
     - role: emit-job-header
       zuul_log_url: "http://logs.openstack.org"
+    - log-inventory
 
 - hosts: all
   pre_tasks:
@@ -17,7 +18,6 @@
     - add-build-sshkey
     - start-zuul-console
     - ensure-output-dirs
-    - log-inventory
 
 - hosts: all
   roles: