ci: Use ninja to build in macOS native CI job

ci/test/00_setup_env_mac_native.sh

@@ -10,6 +10,7 @@ export LC_ALL=C.UTF-8
 # Therefore, `--break-system-packages` is needed.
 export PIP_PACKAGES="--break-system-packages zmq"
 export GOAL="install"
+export CMAKE_GENERATOR="Ninja"
 export BITCOIN_CONFIG="-DBUILD_GUI=ON -DWITH_ZMQ=ON -DWITH_MINIUPNPC=ON -DWITH_NATPMP=ON -DREDUCE_EXPORTS=ON"
 export CI_OS_NAME="macos"
 export NO_DEPENDS=1