[release/9.0] Ensure proper ref count of underlying ocx

[github-actions]

Backport of #12281 to release/9.0

/cc @lonitra

Customer Impact

Upon doing improvements to our interop code, we had missed releasing a pointer to the underlying ocx of the AxHost control, which was causing the underlying ocx to linger even after customer AxHost control is disposed. This causes the destructor of the of the underlying ocx to not get called because it still has a ref count of 1, causing issues with resource management in their application.

Testing

Tested manually with customer repro scenario and added regression test for the scenario.

Risk

Low. Change involves releasing the pointer we missed, correcting the ref count.

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

Attention: Patch coverage is 71.42857% with 4 lines in your changes missing coverage. Please review.

Project coverage is 74.81152%. Comparing base (40bc98a) to head (2479868).
Report is 2 commits behind head on release/9.0.

Additional details and impacted files

@@                  Coverage Diff                  @@
##           release/9.0      #12287         +/-   ##
=====================================================
- Coverage     74.81381%   74.81152%   -0.00230%     
=====================================================
  Files             3022        3022                 
  Lines           630147      630157         +10     
  Branches         46787       46787                 
=====================================================
- Hits            471437      471430          -7     
- Misses          155328      155337          +9     
- Partials          3382        3390          +8     

Flag	Coverage Δ
Debug	74.81152% <71.42857%> (-0.00230%)	⬇️
integration	18.02693% <0.00000%> (-0.00402%)	⬇️
production	47.82223% <33.33333%> (-0.00563%)	⬇️
test	97.00766% <100.00000%> (+0.00007%)	⬆️
unit	44.85537% <33.33333%> (-0.00207%)	⬇️

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