Fix UpDownBase control for dark mode.

[KlausLoeffelmann]

Fixes a regression, where the UpDown control did no longer opt-in to automatic DarkMode theming.

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.82919%. Comparing base (e037b05) to head (7617e8c).
Report is 22 commits behind head on main.

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #13705         +/-   ##
===================================================
+ Coverage   76.75572%   76.82919%   +0.07347%     
===================================================
  Files           3256        3257          +1     
  Lines         642016      642593        +577     
  Branches       47548       47565         +17     
===================================================
+ Hits          492784      493699        +915     
+ Misses        145574      145233        -341     
- Partials        3658        3661          +3     

Flag	Coverage Δ
Debug	76.82919% <100.00000%> (+0.07347%)	⬆️
integration	18.99186% <100.00000%> (+0.00009%)	⬆️
production	51.44113% <100.00000%> (+0.12279%)	⬆️
test	97.41822% <ø> (+0.00103%)	⬆️
unit	48.82020% <100.00000%> (+0.12357%)	⬆️

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