UI: Do not display threaded message boxes on startup

The message boxes that tell you that the browser is initializing or that
you're authenticating with twitch are annoying on startup.  It makes
sense to do it in the settings/autoconfig dialogs where you sort of need
to know what's going on while waiting for it to connect, but on startup
it's not really necessary and can be kind of annoying.

UI/auth-mixer.cpp

@@ -83,7 +83,7 @@ try {
 					5);
 		};
 
-		ExecuteFuncSafeBlockMsgBox(
+		ExecThreadedWithoutBlocking(
 				func,
 				QTStr("Auth.LoadingChannel.Title"),
 				QTStr("Auth.LoadingChannel.Text").arg(service()));
@@ -126,7 +126,7 @@ try {
 				5);
 	};
 
-	ExecuteFuncSafeBlockMsgBox(
+	ExecThreadedWithoutBlocking(
 			func,
 			QTStr("Auth.LoadingChannel.Title"),
 			QTStr("Auth.LoadingChannel.Text").arg(service()));
@@ -205,7 +205,7 @@ void MixerAuth::LoadUI()
 	if (!GetChannelInfo())
 		return;
 
-	OBSBasic::InitBrowserPanelSafeBlock(true);
+	OBSBasic::InitBrowserPanelSafeBlock();
 	OBSBasic *main = OBSBasic::Get();
 
 	std::string url;