Fix Connect_DualMode_DnsConnect_RetrievedEndPoints_Success on Linux (#54681)

Author: antonfirsov

src/libraries/System.Net.Sockets/tests/FunctionalTests/Connect.cs

@@ -129,7 +129,7 @@ public async Task Connect_DualMode_DnsConnect_RetrievedEndPoints_Success()
 
                 var localEndPoint = client.LocalEndPoint as IPEndPoint;
                 Assert.NotNull(localEndPoint);
-                Assert.Equal(IPAddress.Loopback.MapToIPv6(), localEndPoint.Address);
+                Assert.True(localEndPoint.Address.Equals(IPAddress.IPv6Loopback) || localEndPoint.Address.Equals(IPAddress.Loopback.MapToIPv6()));
 
                 var remoteEndPoint = client.RemoteEndPoint as IPEndPoint;
                 Assert.NotNull(remoteEndPoint);