docs(v11): remove StructuredListInput onChange deprecation

[tay1orjones]

This updates the migration guide to reflect the removal of the onChange deprecation

Context

• In v10 StructuredListInput did not actually use or call onChange at all, so we deprecated it for removal in early builds of v11.
• Later on as we continued work on v11, we did a large a11y refactor of the Structured List components and added the onChange call, making it work.
• We initially missed/forgot to remove the deprecation warning, but it has since been removed.

Related: #14254

Changelog

Changed

• update v11.md to reflect current status of onChange StructuredListInput API

Testing / Reviewing

• Check my grammar

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.03%. Comparing base (5020449) to head (1c98be0).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #17530   +/-   ##
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  Coverage   77.03%   77.03%           
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  Files         408      408           
  Lines       13993    13993           
  Branches     4321     4349   +28     
=======================================
  Hits        10779    10779           
  Misses       3041     3041           
  Partials      173      173           

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[emyarod]

looks good to me!