Default RequestParameterConverter#converter doesn't handle RequiresHTMLConversion anymore

The DefaultRequestParameterConverter use to handle properly conversion of requests sent by the WYSIWYG editor which included a RequiresHTMLConversion parameter. Since XWIKI-23205 the default component only handle the conversion of requests containing a RequiresConversion parameter, the older ones are now handled by a component having the html hint.
As a result, code that was relying on injecting the default component is not working properly anymore.

XWIKI-23384 fixes one API method but I forgot to actually fix RequestParameterConverter#convert(ServletRequest).