improve debuging HTTP/2 tests (#94530)

* improve debuging HTTP/2 tests

* line

* feedback

Author: wfurt

src/libraries/Common/src/Interop/Unix/System.Security.Cryptography.Native/Interop.OpenSsl.cs

@@ -805,6 +805,7 @@ private static unsafe void KeyLogCallback(IntPtr ssl, char* line)
                 {
                     s_fileStream.Write(data);
                     s_fileStream.WriteByte((byte)'\n');
+                    s_fileStream.Flush();
                 }
             }
         }

src/libraries/Common/tests/System/Net/Http/GenericLoopbackServer.cs

@@ -94,6 +94,9 @@ public void Close()
             CloseWebSocket();
         }
 
+        public EndPoint? LocalEndPoint => _socket?.LocalEndPoint;
+        public EndPoint? RemoteEndPoint => _socket?.RemoteEndPoint;
+
         public async Task WaitForCloseAsync(CancellationToken cancellationToken)
         {
             while (_websocket != null

src/libraries/Common/tests/System/Net/Http/Http2LoopbackConnection.cs

@@ -43,6 +43,11 @@ private Http2LoopbackConnection(SocketWrapper socket, Stream stream, TimeSpan ti
             _transparentPingResponse = transparentPingResponse;
         }
 
+        public override string ToString()
+        {
+            return $"{this.GetType().Name} {_connectionSocket.LocalEndPoint} <-> {_connectionSocket.RemoteEndPoint}";
+        }
+
         public static Task<Http2LoopbackConnection> CreateAsync(SocketWrapper socket, Stream stream, Http2Options httpOptions)
         {
             return CreateAsync(socket, stream, httpOptions, Http2LoopbackServer.Timeout);