C#: Remove compat method that is now generated

[raulsntos]

• Follow-up to [RTL] Add support for image dynamic updating, padding, tooltips and size in percent. #80410 and C#: Generate and use compat methods #80527.

With #80527 we're now generating compat methods for C# from the ones registered in ClassDB, so it's not needed to add them manually to the Compat.cs file.

PRs that modify Compat.cs should be rebased, so that CI can fail if there are conflicts with the generated compat methods. But going forward there should be no need to modify Compat.cs manually except for cases unsupported by ClassDB (e.g.: compatibility properties).

[AThousandShips]

(Fails without #82368)

[akien-mga]

Thanks!