Remove jitter fix slider

LUS defaults to always on now (if not set by the port). And this option was confusing for most users.

Might increase input latency by one frame, when V-Sync is on and FPS is even above the refresh rate for a moment. (Normal behavior with jitter fix on).

src/port/Engine.cpp

@@ -509,11 +509,8 @@ void GameEngine::ProcessGfxCommands(Gfx* commands) {
 
     time -= fps;
 
-    int threshold = CVarGetInteger("gExtraLatencyThreshold", 80);
-
     if (wnd != nullptr) {
         wnd->SetTargetFps(fps);
-        wnd->SetMaximumFrameLatency(threshold > 0 && target_fps >= threshold ? 2 : 1);
     }
 
     // When the gfx debugger is active, only run with the final mtx