Refactor BindToDeviceSocketMutator.

Only expose a factory function in the header. This limits the
internal gRPC dependency to the .cpp file and simplifies the
implementation.

Bug: 280043032
Test: local build
Change-Id: Ic7ea8dac9935231ceb05bec22c2a5902c50ea8db
diff --git a/automotive/remoteaccess/hal/default/src/RemoteAccessImpl.cpp b/automotive/remoteaccess/hal/default/src/RemoteAccessImpl.cpp
index d525141..b091162 100644
--- a/automotive/remoteaccess/hal/default/src/RemoteAccessImpl.cpp
+++ b/automotive/remoteaccess/hal/default/src/RemoteAccessImpl.cpp
@@ -40,7 +40,7 @@
 
 #ifdef GRPC_SERVICE_IFNAME
     grpcargs.SetSocketMutator(
-            new android::hardware::automotive::remoteaccess::BindToDeviceSocketMutator(
+            android::hardware::automotive::remoteaccess::MakeBindToDeviceSocketMutator(
                     GRPC_SERVICE_IFNAME));
     LOG(DEBUG) << "GRPC_SERVICE_IFNAME specified as: " << GRPC_SERVICE_IFNAME;
     LOG(INFO) << "Waiting for interface: " << GRPC_SERVICE_IFNAME;