[fix] searxng_extra/update/update_engine_descriptions.py (part 1)

Follow up of #2269

The script to update the descriptions of the engines does no longer work since
PR #2269 has been merged.

searx/engines/wikipedia.py
==========================

1. There was a misusage of zh-classical.wikipedia.org:

   - `zh-classical` is dedicate to classical Chinese [1] which is not
     traditional Chinese [2].

   - zh.wikipedia.org has LanguageConverter enabled [3] and is going to
     dynamically show simplified or traditional Chinese according to the
     HTTP Accept-Language header.

2. The update_engine_descriptions.py needs a list of all wikipedias.  The
   implementation from #2269 included only a reduced list:

   - https://meta.wikimedia.org/wiki/Wikipedia_article_depth
   - https://meta.wikimedia.org/wiki/List_of_Wikipedias

searxng_extra/update/update_engine_descriptions.py
==================================================

Before PR #2269 there was a match_language() function that did an approximation
using various methods.  With PR #2269 there are only the types in the data model
of the languages, which can be recognized by babel.  The approximation methods,
which are needed (only here) in the determination of the descriptions, must be
replaced by other methods.

[1] https://en.wikipedia.org/wiki/Classical_Chinese
[2] https://en.wikipedia.org/wiki/Traditional_Chinese_characters
[3] https://www.mediawiki.org/wiki/Writing_systems#LanguageConverter

Closes: https://github.com/searxng/searxng/issues/2330


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