StreamingConnectionFactory should set hostnameVerificationAlgorithm…

… to an empty string (#2988)

Motivation:

There are cases when default algorithm `HTTPS` can be reset if there are no `sniHostname` and no `peerHost`. See
`GrpcSslAndNonSslConnectionsTest` as a reproducer. This flow works well with Netty 4.1, but breaks with Netty 4.2 because Netty uses `HTTPS` by default. If we set it back to `null`, `sun.security.ssl.SSLEngineImpl` ignores it. To disable it later, we should use an empty string.

Modifications:

- Update `StreamingConnectionFactory.withSslConfigPeerHost` to use an empty string instead of `null` when it needs to reset `hostnameVerificationAlgorithm`;

Result:

We can override the previously set endpoint identification algorithm.

servicetalk-http-netty/src/main/java/io/servicetalk/http/netty/StreamingConnectionFactory.java

@@ -95,7 +95,8 @@ static ReadOnlyTcpClientConfig withSslConfigPeerHost(Object resolvedRemoteAddres
             if (sniHostname == null) {
                 if (peerHost == null) {
                     newPeerHost = toHostAddress(inetAddress);
-                    newSniHostname = hostnameVerificationAlgorithm = null;
+                    newSniHostname = null;
+                    hostnameVerificationAlgorithm = "";
                 } else {
                     newPeerHost = peerHost + '-' + toHostAddress(inetAddress);
                     // We are overriding the peerHost to make it qualified with the resolved address. If sniHostname is
@@ -105,7 +106,8 @@ static ReadOnlyTcpClientConfig withSslConfigPeerHost(Object resolvedRemoteAddres
                         newSniHostname = peerHost;
                         hostnameVerificationAlgorithm = sslConfig.hostnameVerificationAlgorithm();
                     } else {
-                        newSniHostname = hostnameVerificationAlgorithm = null;
+                        newSniHostname = null;
+                        hostnameVerificationAlgorithm = "";
                     }
                 }
             } else {