bing_news: parital rollback of c89c05bc

The bing_news bug (discussed in #1838) was caused by wrong language tags, which
was fixed e0c99d9d / no need to change the bing_news search string.

closes: https://github.com/asciimoo/searx/issues/1838



Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>