Add test coverage for ListBox

[Syareel-Sukeri]

Related https://github.com/dotnet/winforms/issues/10453

Proposed changes

• Add unit tests for ListBox to test its properties: PreferredHeight, Text
• Add unit tests for ListBox to test its method: Refresh, SetSelected

Microsoft Reviewers: Open in CodeFlow

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 74.53906%. Comparing base (2a6733d) to head (0db4c15). Report is 13 commits behind head on main.

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #11624         +/-   ##
===================================================
- Coverage   74.55540%   74.53906%   -0.01634%     
===================================================
  Files           3040        3041          +1     
  Lines         629493      629643        +150     
  Branches       46835       46845         +10     
===================================================
+ Hits          469321      469330          +9     
- Misses        156818      156952        +134     
- Partials        3354        3361          +7     

Flag	Coverage Δ
Debug	74.53906% <100.00000%> (-0.01634%)	:arrow_down:
integration	17.88702% <ø> (-0.08302%)	:arrow_down:
production	47.42758% <ø> (-0.07382%)	:arrow_down:
test	96.97610% <100.00000%> (+0.02163%)	:arrow_up:
unit	44.55091% <ø> (+0.03211%)	:arrow_up:

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