GP Backup tidy (connected to ending gamestate)

- Handle removing GP Backups when any game end sequence is started, not just the Podium (in case no Podium exists)
- Guarantee removal in M_StartCup out-of-entries failure state

src/g_game.c

@@ -4651,6 +4651,8 @@ void G_EndGame(void)
 	// Only do evaluation and credits in singleplayer contexts
 	if (!netgame && grandprixinfo.gp == true)
 	{
+		G_HandleSaveLevel(true);
+
 		if (nextmap == NEXTMAP_CEREMONY) // end game with ceremony
 		{
 			if (K_StartCeremony() == true)

src/menus/transient/cup-select.c

@@ -155,7 +155,8 @@ static void M_StartCup(UINT8 entry)
 				NULL, MM_NOTHING, NULL, NULL
 			);
 
-			G_HandleSaveLevel(true);
+			if (FIL_FileExists(gpbackup))
+				remove(gpbackup);
 
 			return;
 		}

src/p_setup.c

@@ -8358,7 +8358,7 @@ void P_PostLoadLevel(void)
 
 	P_RunCachedActions();
 
-	G_HandleSaveLevel(gamestate == GS_CEREMONY);
+	G_HandleSaveLevel(false);
 
 	if (marathonmode & MA_INGAME)
 	{