Map the Kabyle locale to the language code `kab` for Crowdin sync

What does this MR do?

Currently Crowdin is syncing the Kabyle language with the language code kab_KAB. This locale code cannot be detected by gettext, as this tool detects locale codes that only have 2 characters after the underscore. https://github.com/ruby-gettext/gettext/blob/28046d1/lib/gettext/tools/task.rb#L520

This is causing the gettext:regenerate command to delete the locale/kab_KAB/gitlab.po file every time it is run.

This change:

1. Update the Crowdin config to map kab_KAB to just kab
2. Deletes kab_KAB locale file (which currently has 0% translation anyway).

Issue: #235511 (closed)

Screenshots

I tested this config on a personal project and synced it with Crowdin and got the following filepath:

Does this MR meet the acceptance criteria?

Conformity

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Availability and Testing

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• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

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• ~~Label as security and @ mention @gitlab-com/gl-security/appsec~~
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
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