perf: appimage (dont')-preload optimisation

[mmeeks]

Richdocuments-code uses an appimage for a demo version of COOL; it has lower security and no websocket it also tends to live on the same webserver as Nextcloud + Database etc. It tends to have many fewer live / concurrent users and be used as a demo.

So - we should shrink it's active memory footprint.

We should avoid as much pre-loading as much in this configuration - some tweaks to desktop/source/lib/init.cxx 's preload to avoid eg. pre-loading dictionaries and translations would be a good idea - though we'd need to ensure that they load on-demand then.