[Bug]: High storage space usage

### What Monal Release channel are you using? AppStore ### iOS system version (if applicable) 15.8.8 ### Monal version 6.4.21 (1092) ### Used XMPP server (domain) debian.org ### Which XMPP-Server software are you using? Prosody ### XMPP Server Software Version 13.0.1 ### How many accounts are you using in Monal? 1 ### What happened? Hi! I've been using Monal for a while and it works great, but I noticed that for some reason it takes a big amount of storage space after just a few days of usage. I'm not in big group chats, nor send almost any media. Still, Monal takes up 400 MB of storage for its app data, which on my 16 GB of storage filled by iOS plus its "system data" taking up 12 GB feels like a lot. How can I debug what is taking up all the space? Bye! ### FAQ - [x] I have [checked the FAQ](https://github.com/monal-im/Monal/wiki/FAQ---Frequently-Asked-Questions) for my issue ### Considerations for XMPP users - [x] I have checked if my issue can be solved with [Considerations for XMPP users](https://github.com/monal-im/Monal/wiki/Considerations-for-XMPP-users) and [Considerations for XMPP server admins](https://github.com/monal-im/Monal/wiki/Considerations-for-XMPP-server-admins) ### XEP-Check - [x] I have checked that at least XEP-198, XEP-0280, XEP-0352, XEP-0357, XEP-0313 and XEP-0163 are activated on my server and shown as 'green' under Settings --> Account--> (i) in advanced settings ### Notifications-Menu - [x] I have checked that all checkmarks are present under Settings --> Notifications