Deprecate qualified search terms in the search parameter

The discussion in #21366 (moved) made it clear that qualified search terms aren't as good as the regular parameters.

• They are a weak duplicate of functionality offered by the regular parameters.
• There is no support for spaces unlike the regular parameters.
• Not all parameters are supported as qualified search terms.
• It places too much functionality into one parameter (look at the size of the search parameter paragraph compared to the other parameters at https://onionoo.torproject.org/#methods).

FWICT the regular parameters offer more functionality than the qualified search terms so the later can safely be deprecated without loss of functionality.