Fix type of constantsToExport arg (#54718)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/54718

The cast in `constantsToExport` is unnecessary if we actually use the right type here, without the `Builder` suffix.

Not a breaking change, since Objective-C seemingly doesn't enforce these parameter constraints.

Changelog: [Internal]

Reviewed By: sammy-SC

Differential Revision: D87980865

fbshipit-source-id: c9052e219fdf44d012583fcaa94b10b7c189b510