Use better local variable name

Renamed local `serverMessage` back to `closeStatusDescription` per PR feedback.
Co-authored-by: Natalia Kondratyeva <[email protected]>

Author: IDisposable

src/libraries/System.Net.WebSockets/tests/WebSocketCloseTests.cs

@@ -69,8 +69,8 @@ public async Task ReceiveAsync_ValidCloseStatus_Success(WebSocketCloseStatus clo
                 await server.SendAsync(sendBytes.AsMemory(), WebSocketMessageType.Text, WebSocketMessageFlags.DisableCompression, CancellationToken);
 
                 // and then server-side close with the test status
-                string serverMessage = "CloseStatus " + closeStatus.ToString();
-                await server.CloseOutputAsync(closeStatus, serverMessage, CancellationToken);
+                string closeStatusDescription = "CloseStatus " + closeStatus.ToString();
+                await server.CloseOutputAsync(closeStatus, closeStatusDescription, CancellationToken);
 
                 // get the hello from the client (after the close message was sent)
                 WebSocketReceiveResult result = await client.ReceiveAsync(new ArraySegment<byte>(receiveBuffer), CancellationToken);