When we upgraded to Rails 7 in commit 8596f1539, we broke the custom
locales since now all nested folders in `config/locales/` are loaded by
default [1]. This meant that the custom folder was now loaded before any
languages whose code alphabetically goes after the word "custom".
As a workaround, we're overwriting the default locales paths so they
don't include the custom folder. We're doing this step before the
`add_locales` initializer; that is, before the default locales paths are
used.
Unfortunately, I haven't found a way to add a test for this behavior,
since we would need to add a file in `config/locales/custom` that
overwrites an internationalization key for an existing language, but
only during a specific test, and the i18n load path is evaluated when
the application starts up.
[1] See pull request 41872 in https://github.com/rails/rails/
75ebc1bd98