[fix] openstreatmap: load thumbnail from uploads.wikimedia.org

Openstreatmap images are now loaded from uploads.wikimedia.org instead of
commons.wikimedia.org to prevent redirects.

With `image_proxy` enabled images from commons.wikimedia.org cant be loaded
since they are redirected.  We already discussed this issue [875] and
@tiekoetter fixed this issue in PR [878].

Related-to:
- [875] https://github.com/searxng/searxng/issues/875
- [878] https://github.com/searxng/searxng/pull/878


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