Ever growing directories

Since a long time we discovered growing directories

~/tmp/check_mk/wato/activation
AND
~/var/check_mk/site_configs

Let me mention that the site is running on 2.0.0p20. However the first setup must be a long time ago (probably 1.2* version). The site has always been upgraded since then.

We assume that we are missing some cron tasks that should do a proper cleanup. We have very old files (older than one year). Is there any cleanup task that is missing?