UI: Remove default values from multitrack-video.hpp

These are always overridden in goliveapi-postdata.cpp

Co-authored-by: Ruwen Hahn <[email protected]>

UI/models/multitrack-video.hpp

@@ -202,8 +202,8 @@ struct Preferences {
 };
 
 struct PostData {
-	string service = "IVS";
-	string schema_version = "2023-05-10";
+	string service;
+	string schema_version;
 	string authentication;
 
 	Capabilities capabilities;