[fix] complete overhaul of the DuckDuckGo engines

DDG has reimplemented its bot protection, and the DDG engines "images", "news"
and "videos" no longer work in SearXNG and DDG-Web access often ends with a
CAPTCHA.

Related:

- issue 4824
- https://github.com/ggfevans/searxng/blob/mod-sidecar-harvester/docs/ddg-bot-detection-research.md

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

searx/settings.yml

@@ -829,24 +829,21 @@ engines:
 
   - name: duckduckgo images
     engine: duckduckgo_extra
-    categories: [images, web]
+    categories: [images]
     ddg_category: images
     shortcut: ddi
-    disabled: true
 
   - name: duckduckgo videos
     engine: duckduckgo_extra
-    categories: [videos, web]
+    categories: [videos]
     ddg_category: videos
     shortcut: ddv
-    disabled: true
 
   - name: duckduckgo news
     engine: duckduckgo_extra
-    categories: [news, web]
+    categories: [news]
     ddg_category: news
     shortcut: ddn
-    disabled: true
 
   - name: duckduckgo weather
     engine: duckduckgo_weather