GUI: Remove old translation files, reorganize translations

[GChuf]

I have only noticed that all the "old" translation files are being used for v19 after being mentioned in #17027.
Due to some reorganizing on transifex, some language files should never have ended in v19. The correct way to update would be to delete all existing translation files and run the script afterwards.
This is the result.

FWIW: Why are there less files than before? It's because there was a lot of duplication on transifex. For example, Korean would be translated into (ko) as well as (ko_KR). I've deleted ko_KR in such cases, and merged such translations together to get one, more completed translation file.

I wasn't sure how to deal with 019 appropriately, so I made this PR to master.

[GChuf]

@laanwj please take a look.
note: this includes the zh_TW "fix" as well from the aforementioned issue.

[DrahtBot]

The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

Conflicts

Reviewers, this pull request conflicts with the following ones:

• #16966 (ui: make send a wizard by Sjors)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

[laanwj]

• Please change this on Transifex, never manually on the branch. The script will automatically add and remove translations to synchronize with transifex.
• We do not do translation updates on master (see contrib: Bump gitian descriptors for 0.20 #17049 (comment)).

[laanwj]

The correct way to update would be to delete all existing translation files and run the script afterwards. This is the result.

Wait, I'm pretty sure the script already does this? If not, we need to fix the script so this keeps happening automatically.
You're right, it doesn't!

[laanwj]

ref bitcoin-core/bitcoin-maintainer-tools#39