[release/9.0] [RC2] Revert #11520 to fix a MenuItem issue

[KlausLoeffelmann]

Backport the Menu Item Fix (#11920) into .NET 9RC1 to fix #11909.

• MenuStrip highlight "sticks" after menu item is activated, also affects keyboard focus · Issue #11909 · dotnet/winforms (github.com)

Customer Impact

This is a breaking change, and it is specifically blocking Rick Brewster (the maintainer of Paint .NET) to migrate Paint.NET to .NET 9, which is another reason why I would like this to get in into RC1 already, to unblock all folks, who have been started to migrate to .NET 9 and are blocked by this.

Workaround: There is none.

Regression?

• Yes from the previous release
• [] No

Risk

• High
• Medium
• Low –The changes are isolated and are not affecting anything else. This PR is effectively a revert of the A11Y PR, which needs a different approach. We are not considering the A11Y issue High Prio issue, so it can be addressed again in .NET 10.

Verification

• Manual testing – Several manual tests made sure that this issue has been mitigated.
• Automated

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 74.79167%. Comparing base (97322a7) to head (dd475b5).
Report is 1 commits behind head on release/9.0.

Additional details and impacted files

@@                  Coverage Diff                  @@
##           release/9.0      #11931         +/-   ##
=====================================================
- Coverage     74.79485%   74.79167%   -0.00319%     
=====================================================
  Files             3019        3019                 
  Lines           630034      630010         -24     
  Branches         46781       46777          -4     
=====================================================
- Hits            471233      471195         -38     
- Misses          155425      155428          +3     
- Partials          3376        3387         +11     

Flag	Coverage Δ
Debug	74.79167% <0.00000%> (-0.00319%)	⬇️
integration	18.03090% <0.00000%> (+0.00117%)	⬆️
production	47.77920% <0.00000%> (-0.00828%)	⬇️
test	97.00750% <ø> (-0.00088%)	⬇️
unit	44.80500% <0.00000%> (-0.00713%)	⬇️

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