Fix OpenGlControlBase: Ensure _updateQueued is set to false when DoCleanup() is called

[laolarou726]

What does the pull request do?

Ensure _updateQueued is set to false when DoCleanup() is called.
Currently, when OpenGlControlBase is detached from the visual tree. Method DoCleanup() will get called immediately.
However, in this method it doesn't set _updateQueued to false, which will fail the following check:

OpenGlControlBase.cs at Line #226:

public void RequestNextFrameRendering()
{
    if ((_initialization == null || _initialization is { Status: TaskStatus.RanToCompletion }) &&
        !_updateQueued) // This check will always failed because _updateQueued is true after DoCleanup()
    {
        _updateQueued = true;
        _compositor?.RequestCompositionUpdate(_update);
    }
}

As the result, the OpenGlControl will never get any frame output after it re-attached to the visual tree.

What is the current behavior?

Now the cleanup method will ensure to set the _updateQueud to false in DoCleanup().

What is the updated/expected behavior with this PR?

Now the control that using OpenGL will still work after the control is re-attached to the visual tree.