Tails Installer should not raise an exception when a too small USB drive is detected

This is a follow-up on #9130 (closed), after discussing how it should work on #9734 (closed).

Feature Branch: kurono:Bug/9886-installer-should-not-raise-exception

Original created by @intrigeri on 9886 (Redmine)

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