Make deploy script variable `{FLUSH_FASTCGI_CACHE}` available on production sites

Issue

On my staging site I have added the snippet {FLUSH_FASTCGI_CACHE} to the deployment script in order to clear the fastcgi cache which works and successfully clears the cache at the end of the deployment. On my production site I would like to the same. Sadly, this does not work. The synchronization logs say: ploi-cf9f3448dae791fbdcc99d632ea1b39b.sh: line 28: {FLUSH_FASTCGI_CACHE}: command not found

The list of available Deploy script variables on the General tabs looks different for staging and production as well. On staging FLUSH_FASTCGI_CACHE is listed under the General drop-down whereas it is missing on the production site.

Expection

All deployment variable that are available on staging sites are available on production sites as well