[clean] Internet Archive Scholar search API no longer exists

Engine was added in #2733 but the API does no longer exists. Related:

- https://github.com/searxng/searxng/issues/4038

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

searx/settings.yml

@@ -1622,11 +1622,6 @@ engines:
     api_site: 'askubuntu'
     categories: [it, q&a]
 
-  - name: internetarchivescholar
-    engine: internet_archive_scholar
-    shortcut: ias
-    timeout: 15.0
-
   - name: superuser
     engine: stackexchange
     shortcut: su