base-test: 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: I52aaf33ce68bbc2a07fabe3d84b0daffa6e70f26

playbooks/base-test/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: