Remove obsolete update-piwik script

roles/account-automation-backend-web/meta/main.yml

@@ -18,7 +18,5 @@ dependencies:
           calendar: "*:1,21,41"
         - name: update-mysql-passwords
           calendar: "*:26,56"
-        - name: update-piwik
-          calendar: "daily"
         - name: warn-vulnerabilities
           calendar: "weekly"