Replace CountAttributedType::getAttributeName() with something that returns the actually spelling in the source code

[delcypher]

In #106321 CountAttributedType::getAttributeName() will be introduced that gets the name of an attribute (with or without a macro prefix).

This method is not really ideal. The method doesn't actually return the spelling of the attribute used in the source code (e.g. they could be using their own macro).

This issue tracks replacing CountAttributedType::getAttributeName() with something better. Unfortunately I don't think we can fix this until #113582 is fixed because we would need a way to find the TypeLoc for an attribute in order to determine how it is spelt in the user's code.