[I18N] *: remove .tx/config

After the switch to Weblate, we now only use the `.weblate.json` file
instead of the previous `.tx/config` file.

closes #14491

X-original-commit: e2aac4f
Related: odoo/odoo#225467
Related: odoo/enterprise#93872
Related: odoo/design-themes#1139
Signed-off-by: Tiffany Chang (tic) <[email protected]>
Signed-off-by: Dylan Kiss (dyki) <[email protected]>

Author: dylankiss