Release IO buffer on outbound error

`OutboundMessageHandler` writes message to `ByteBuf`. It allocates a
dedicated IO buffer for this. Writing can fail for various reasons
(unsupported byte arrays, etc).

Previously this IO buffer has not been released in case of an error.
When writing is successful IO buffer is released by then channel pipeline.

This commit makes `OutboundMessageHandler` release buffer before
rethrowing the exception.

Author: lutovich

driver/src/main/java/org/neo4j/driver/internal/async/outbound/OutboundMessageHandler.java

@@ -65,14 +65,14 @@ protected void encode( ChannelHandlerContext ctx, Message msg, List<Object> out
         try
         {
             writer.write( msg );
+            output.stop();
         }
         catch ( Throwable error )
-        {
-            throw new EncoderException( "Failed to write outbound message: " + msg, error );
-        }
-        finally
         {
             output.stop();
+            // release buffer because it will not get added to the out list and no other handler is going to handle it
+            messageBuf.release();
+            throw new EncoderException( "Failed to write outbound message: " + msg, error );
         }
 
         if ( log.isTraceEnabled() )