In this case, is there a reason that you would want the code displayed instead of the description? I like to think of the Code like a field name, and the Description like a field alias, so normally that's what you would want displayed in the dropdown.
Like you, I found this article about changing the settings to display the code in ArcMap, but I am also not finding this same functionality in ArcGIS Pro. It would be interesting to know if this is planned for a future release, or if we're both just missing something!
In the meantime, if you really want your dropdown to display (for example) "RES" instead of "Reserved Assigned Parking", you can just put RES in the description field.
Best,
Katie
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