Fix class names in ApiDefinitions.cs

> it would be nice to fix the currently mismatched class names. It actively breaks some advanced scenarios like non-trimmed Debug apps on iOS with `Registrar=managed-static`. The Xamarin build creates a bridge code that tries to statically bind to the non-existing symbols and fails to load.

_Originally posted by @filipnavara in https://github.com/getsentry/sentry-dotnet/pull/3450#discussion_r1668159503_