Ensure rsyncd PID file is removed during overcloud updates

During an overcloud update it might happen that the rsyncd container
gets killed & restarted, leaving a PID file from rsyncd. rsyncd won't
start because of this, which results in a container restarting loop.

This patch ensures the PID file is absent to fix this.

Closes-Bug: 1734674
Change-Id: Ie5b28005f1079e432cfca6c31d28295174e06986
(cherry picked from commit 570c957412)

docker/services/swift-storage.yaml

@@ -515,3 +515,8 @@ outputs:
         - name: Restart xinetd service after rsync removal
           tags: step2
           service: name=xinetd state=restarted
+      update_tasks:
+        - name: Ensure rsyncd pid file is absent
+          file:
+            path: /var/run/rsyncd.pid
+            state: absent