Remove flaky channelRead_Normal test that wasn't doing much

Patch by Adam Holmberg, reviewed by brandonwilliams for CASSANDRA-15965

test/unit/org/apache/cassandra/streaming/async/StreamingInboundHandlerTest.java

@@ -87,18 +87,6 @@ public void tearDown()
         channel.close();
     }
 
-    @Test
-    public void channelRead_Normal()
-    {
-        Assert.assertEquals(0, buffers.unsafeAvailable());
-        int size = 8;
-        buf = channel.alloc().buffer(size);
-        buf.writerIndex(size);
-        channel.writeInbound(buf);
-        Assert.assertEquals(size, buffers.unsafeAvailable());
-        Assert.assertFalse(channel.releaseInbound());
-    }
-
     @Test
     public void channelRead_Closed()
     {