These engines override the user agent manually using `gen_useragent`, although that's already done in the online preprocessor that runs before the actual `request(query, params)` method is called. Hence, this call is duplicated.
Related:
- https://github.com/searxng/searxng/pull/4990#discussion_r2195142838
Fixes the semantic scholar engine by extracting a ui version token.
BTW: remove html tags from the content.
Author's checklist:
- they are ratelimiting very fast, if you do approx more than 2 requests per
minute, you have to wait some time again...
- they also have an official api at api.semanticscholar.org, but it's ratelimits
are even harder
Closes: https://github.com/searxng/searxng/issues/4685
