broken LUKS password verification breaks disko-install

#1105 actually broke the installation process instead just "fixing" #1102. Because now when `disko-install` gets called & users insert two different passphrases, the installation does not abort but continues *without formatting & mounting* anything, meaning that the system configuration is installed into a sub-directory of the root mount. The user is not asked for This is the current verification code snippet after #1105: https://github.com/nix-community/disko/blob/916506443ecd0d0b4a0f4cf9d40a3c22ce39b378/lib/types/luks.nix#L144-L160 IMO this issue could use two fixes: - disko-install should abort the installation if the format scripts exists with any error code - preventing that the installation silently ignores any errors while formatting/mounting - `exit 1` in line 151 should be replaced with `return 1` - so that the until block at line 157 can actually do its work - so that the user can actually retype the password on a mismatch