Removed use of deprecated FutureHandle in Dynamic Links stub.
Removed use of deprecated FutureHandle in Dynamic Links stub.

PiperOrigin-RevId: 264683407

firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk