Remove timeout conn on net.Dialer (#7590)

This PR also removes conn_bug_21133 workaround
which is not valid anymore, all we need is deadline
connection with server in place

Fixes #7503

cmd/rest/client.go

@@ -89,12 +89,7 @@ func newCustomDialContext(timeout time.Duration) func(ctx context.Context, netwo
 			DualStack: true,
 		}
 
-		conn, err := dialer.DialContext(ctx, network, addr)
-		if err != nil {
-			return nil, err
-		}
-
-		return xhttp.NewTimeoutConn(conn, timeout, timeout), nil
+		return dialer.DialContext(ctx, network, addr)
 	}
 }