Fix broken BufferHubQueueTest.TestRemoveBuffer

Under certain condition, it's unsafe to nullify the consumer channel
within producer channel's destructor.

Bug: 38137191
Bug: 70046255
Bug: 70912269
Test: buffer_hub-test, buffer_hub_queue-tests, buffer_hub_queue_producer-tesst
Change-Id: Ifbed85e687e71340f6876e4e85c792ae1d6b06f6
diff --git a/libs/vr/libbufferhub/buffer_hub-test.cpp b/libs/vr/libbufferhub/buffer_hub-test.cpp
index 3ce5c9f..660a200 100644
--- a/libs/vr/libbufferhub/buffer_hub-test.cpp
+++ b/libs/vr/libbufferhub/buffer_hub-test.cpp
@@ -769,9 +769,14 @@
 
   auto s3 = p->CreateConsumer();
   EXPECT_FALSE(s3);
+  // Note that here the expected error code is EOPNOTSUPP as the socket towards
+  // ProducerChannel has been teared down.
   EXPECT_EQ(s3.error(), EOPNOTSUPP);
 
   s3 = c->CreateConsumer();
   EXPECT_FALSE(s3);
-  EXPECT_EQ(s3.error(), EOPNOTSUPP);
+  // Note that here the expected error code is EPIPE returned from
+  // ConsumerChannel::HandleMessage as the socket is still open but the producer
+  // is gone.
+  EXPECT_EQ(s3.error(), EPIPE);
 }