Error message on not-enough-free-space in Tails Upgrader is confusing

It’s unclear to users that (or why) the system partition has limited space, independently from the full USB stick. See for example:

Some work can probably be done on this error message.

Original created by @sajolida on 11628 (Redmine)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information