UI: Set default container for beta builds to hybrid MP4

UI/window-basic-main.cpp

@@ -1549,7 +1549,7 @@ extern void CheckExistingCookieId();
 #elif OBS_RELEASE_CANDIDATE == 0 && OBS_BETA == 0
 #define DEFAULT_CONTAINER "mkv"
 #else
-#define DEFAULT_CONTAINER "fragmented_mp4"
+#define DEFAULT_CONTAINER "hybrid_mp4"
 #endif
 
 bool OBSBasic::InitBasicConfigDefaults()