Unified source control cancel operation

When switching source control settings from the Source Control button and toolbar, the same operation produces different results. Licensees have requested that the behavior should be consistent.

Two videos show their differences. When operating a source control button, the settings are retained even if the window is closed. When selecting from the toolbar, those settings are always disabled. Therefore, when we close the window, the source control is always disconnected. It is hoped that the previous settings can be maintained. 

1. Connect the Editor to a Source Control Provider (ex P4)
2. Click on the Editor bottom right 'Source Control' button and select "Change Source Control Settings..."
3. This open a windows with our current settings. Close the window with the top right X without changing anything. Notice that the previous source control provider is preserved (button text remains green).
4. Go to the Editor top menu: Tools -> Change Source Control Settings...
5. This open the same windows a previously, but this time, your actual source control is not set.
6. Close the window with the X without changing anything. Notice now that your source control is off even if you didn't change anything.

Expected: If the user cancel (close the window without changing anything) we expect the source control to remain unchanged, just like when the user click on the bottom right button.