[6.x] chosen removal incomplete and not documented in migration docs

[ramalama]

chosen.js got removed in 6.0 ( Tracker 45018) and the files are removed on upgrade from 5.4.

FormBehavior:chosen still exists and is deprecated, removal planned for 7.0 according to comment in code

I cannot find any notice of the removal in migrations doc

Also the deactivation of compat plugin in 5.4 did not point to this error.

The Example for the replacement in FormBehavior contains non working code: WebAssetManaget doesn't have a enableAsset method.

JHtml::_('formbehavior.chosen',[...]) is still used in com_weblinks and com_search

[dgrammatiko]

Removal of FormBehavior:chosen was planned for 6.0 but somehow slipped and then everything that wasn't removed in 6.0 got a new deprecation for 7.0 (#46367)

JHtml::_('formbehavior.chosen',[...]) is still used in com_weblinks and com_search

Weblinks doesn't use chosen (https://github.com/joomla-extensions/weblinks/tree/5.x-dev), com_search it is but I guess it's abandoned Nothing done the last 2 years (https://github.com/joomla-extensions/search/commits/main/)