Remove /hosts from log outputs

Change I754637115f8c7469efbc1856e88bbcb6fb83b4ce moved a bunch of log
collection to use "stage-output".  This uses "fetch-output" which
automatically puts these logs in hostname subdirectories; but it does
not have an option to put it in hosts/hostname as we were doing with
the other logs.

Although we could add such support, it probably doesn't make sense as
most other multinode jobs will have the same layout with the host logs
at the top level.  Remove the intermediate "/hosts/" directory on
system-config jobs so all logs remain at the top level, and we don't
have this confusing split as to where logs are for each host.

Change-Id: I56bd67c659ffb26a460d9406f6f090d431c8aa79

playbooks/zuul/run-base-post.yaml

@@ -2,7 +2,7 @@
   tasks:
     - name: Make log directories for testing hosts
       file:
-        path: "{{ zuul.executor.log_root }}/hosts/{{ item }}/logs"
+        path: "{{ zuul.executor.log_root }}/{{ item }}/logs"
         state: directory
         recurse: true
       loop: "{{ query('inventory_hostnames', 'all') }}"
@@ -12,7 +12,7 @@
         path: "{{ item }}"
         state: directory
       with_items:
-        - "{{ zuul.executor.log_root }}/hosts/bridge.openstack.org/ara-report"
+        - "{{ zuul.executor.log_root }}/bridge.openstack.org/ara-report"
 
 - hosts: all
   tasks:
@@ -49,7 +49,7 @@
   tasks:
     - name: Set log directory
       set_fact:
-        log_dir: "{{ zuul.executor.log_root }}/hosts/{{ inventory_hostname }}"
+        log_dir: "{{ zuul.executor.log_root }}/{{ inventory_hostname }}"
 
       # Because during the test we run ansible as root, we need
       # to allow ourselves permissions to copy the results