[FIX] web_refresher: remove broken pt_BR.po stub

The file has no PO header (msgfmt --check reports a fatal error) and
its 2 entries are untranslated (empty msgstr). Removing it lets Weblate
regenerate a valid file when translations arrive.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: Guilherme Eller