core: re-add back in orphan wrapper

Author: carl-mastrangelo

core/src/main/java/io/grpc/internal/AbstractManagedChannelImplBuilder.java

@@ -380,15 +380,15 @@ protected String checkAuthority(String authority) {
 
   @Override
   public ManagedChannel build() {
-    return new ManagedChannelImpl(
+    return new ManagedChannelOrphanWrapper(new ManagedChannelImpl(
         this,
         buildTransportFactory(),
         // TODO(carl-mastrangelo): Allow clients to pass this in
         new ExponentialBackoffPolicy.Provider(),
         SharedResourcePool.forResource(GrpcUtil.SHARED_CHANNEL_EXECUTOR),
         GrpcUtil.STOPWATCH_SUPPLIER,
         getEffectiveInterceptors(),
-        CallTracer.getDefaultFactory());
+        CallTracer.getDefaultFactory()));
   }
 
   // Temporarily disable retry when stats or tracing is enabled to avoid breakage, until we know