Codefix: Rename breakdown setting value string

[2TallTyler]

Motivation / Problem

The value strings for the vehicle breakdowns setting have the prefix DISASTER, but the strings are only used for breakdowns. Disasters are boolean settings, so they have no value strings.

(I am working on something that touches these strings, but this is wrong so I see no reason why we shouldn't just fix it anyway.)

Description

Rename the strings in all languages to say BREAKDOWNS without changing their contents. (As per the eints docs, this is allowed.)

Limitations

Checklist for review

Some things are not automated, and forgotten often. This list is a reminder for the reviewers.

• The bug fix is important enough to be backported? (label: 'backport requested')
• This PR touches english.txt or translations? Check the guidelines
• This PR affects the GS/AI API? (label 'needs review: Script API')
  • ai_changelog.hpp, game_changelog.hpp need updating.
  • The compatibility wrappers (compat_*.nut) need updating.
• This PR affects the NewGRF API? (label 'needs review: NewGRF')
  • newgrf_debug_data.h may need updating.
  • PR must be added to API tracker