Firebase Kokoro: Fixed include dir for nanopb and unity ios build
Firebase Kokoro: Fixed include dir for nanopb and unity ios build

PiperOrigin-RevId: 281568568

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