fix(mastercontainer): run session-deduplicator as www-data

The session-deduplicator only touches files under /mnt/docker-aio-config/session/, which is already owned by www-data, so running it as root grants more privilege than it needs. Dropping to www-data reduces the number of root-owned processes in the mastercontainer and follows least-privilege for the supervisord program set.

Containers/mastercontainer/supervisord.conf

@@ -54,7 +54,7 @@ stdout_logfile_maxbytes=0
 stderr_logfile=/dev/stderr
 stderr_logfile_maxbytes=0
 command=/session-deduplicator.sh
-user=root
+user=www-data
 
 [program:domain-validator]
 # Logging is disabled as otherwise all attempts will be logged which spams the logs