Currently, only stable releases see their translations updated. This has resulted in master accumulating outdated stuff for years, which can be confusing for users testing master on runbot. This one-shot commit resynchronizes master translations based on the content from 16.0 and removes empty PO files (i.e. no longer containing translations). closes odoo/odoo#121629 Related: odoo/enterprise#41171 Signed-off-by: Martin Trigaux (mat) <mat@odoo.com>