datapath_winuser: query RioDispatch only if we are using Rio

[jianye-chen]

Description

The WSAIoctl call for RioDispatch might fail, but it should not block initialization if we have already decided not to use Rio.

Testing

Existing tests do not cover the issue fixed by this PR.

Documentation

N/A

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.57%. Comparing base (1d2b6bd) to head (cea3c78).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4793      +/-   ##
==========================================
- Coverage   86.70%   86.57%   -0.14%     
==========================================
  Files          56       56              
  Lines       17400    17400              
==========================================
- Hits        15087    15064      -23     
- Misses       2313     2336      +23     

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[nibanks]

Description

The WSAIoctl call for RioDispatch might fail, but it should not block initialization if we have already decided not to use Rio.

Thanks for making this PR! Can you describe the environment you're running where this query fails? cc @mtfriesen