Gate: get full process list from host

This PS adds the ps command to the gate log collection task.

Change-Id: Ife1710854547b28a6dfa6b3e4d527ebf4d04179b

tools/gate/playbooks/gather-host-logs/tasks/main.yaml

@@ -26,6 +26,7 @@
           mount > {{ logs_dir }}/system/mount.txt
           docker images > {{ logs_dir }}/system/docker-images.txt
           brctl show > {{ logs_dir }}/system/brctl-show.txt
+          ps aux --sort=-%mem > {{ logs_dir }}/system/ps.txt
   args:
     executable: /bin/bash
   ignore_errors: True