UI: Add support for Twitch "Auto" server in auto-config

Uses the "Auto" server automatically for Twitch rather than doing a
region-based test on multiple servers.

UI/window-basic-auto-config-test.cpp

@@ -246,8 +246,10 @@ void AutoConfigTestPage::TestBandwidthThread()
 		GetServers(servers);
 
 	/* just use the first server if it only has one alternate server,
-	 * or if using Mixer due to its "auto" server */
-	if (servers.size() < 3 || wiz->serviceName == "Mixer.com - FTL")
+	 * or if using Twitch/Mixer due to the "auto" option */
+	if (servers.size() < 3 ||
+	    wiz->service == AutoConfig::Service::Twitch ||
+	    wiz->serviceName == "Mixer.com - FTL")
 		servers.resize(1);
 
 	/* -----------------------------------*/

UI/window-basic-auto-config.cpp

@@ -365,8 +365,7 @@ void AutoConfigStreamPage::ServiceChanged()
 		return;
 
 	std::string service = QT_TO_UTF8(ui->service->currentText());
-	bool regionBased = service == "Twitch" ||
-	                   service == "hitbox.tv";
+	bool regionBased = service == "hitbox.tv";
 	bool testBandwidth = ui->doBandwidthTest->isChecked();
 	bool custom = ui->streamType->currentIndex() == 1;
 
@@ -659,19 +658,7 @@ bool AutoConfig::CanTestServer(const char *server)
 	if (!testRegions || (regionUS && regionEU && regionAsia && regionOther))
 		return true;
 
-	if (service == Service::Twitch) {
-		if (astrcmp_n(server, "US West:", 8) == 0 ||
-		    astrcmp_n(server, "US East:", 8) == 0 ||
-		    astrcmp_n(server, "US Central:", 11) == 0) {
-			return regionUS;
-		} else if (astrcmp_n(server, "EU:", 3) == 0) {
-			return regionEU;
-		} else if (astrcmp_n(server, "Asia:", 5) == 0) {
-			return regionAsia;
-		} else if (regionOther) {
-			return true;
-		}
-	} else if (service == Service::Hitbox) {
+	if (service == Service::Hitbox) {
 		if (strcmp(server, "Default") == 0) {
 			return true;
 		} else if (astrcmp_n(server, "US-West:", 8) == 0 ||