Chat export 2000 MiB limit too low for attachments

### Your use case

#### What would you like to do?
I would like to export my complete chat history but currently there's a limit of 2 000 MiB
This seems kind of like an arbitrary limit, though I understand that getting all the files and zipping them on the client side could get problematic for very big exports.
Unfortunately a 1:1 chat that is 4 years old can easilly have a larger footprint like thsi

#### How would you like to achieve it?
Allow more than 2 000 MiB of data to be exported

### Have you considered any alternatives?

An alternative would be to allow paginating the export, I don't mind getting part1 part2 part3 zips each 2 GB in size.

Or if we could select date ranges like https://github.com/vector-im/element-web/issues/19310 I could manually try split it up (though that would be a pain)

### Additional context

_No response_