graphics: address performance regression with Image Resize (#504)

## Link to GitHub Issue, if one exists
Regressed by #401 

## Description of change
Two things from testing SDVX Live2D -

1. ColorFill is almost always too expensive and will lead to drops
1. Scale factor of 0.5 causes GPU to sync and causes drops

(ARGB/XRGB doesn't matter, linear filtering doesn't matter)

1 is fixed by removing ColorFill calls on every frame - instead only do
this once when the user changes the duplicate option (on the next frame)

2 is fixed by updating the UI (limit the slider) though people can
ctrl+click to override these slider limits.

The warning label will be kept with slightly reworded text.

## Testing
tested in sdvx eg final (sudden death) - on my RTX 4070, my FPS is rock
solid 120 fps even with image resize on now.

src/spice2x/cfg/screen_resize.cpp

@@ -81,18 +81,7 @@ namespace cfg {
         
         load_bool_value(doc, root + "enable_screen_resize", this->enable_screen_resize);
         if (this->enable_screen_resize) {
-            if (avs::game::is_model("KFC")) {
-                log_warning(
-                    "ScreenResize",
-                    "Image Resize feature enabled for SDVX; enabling this is known to significantly "
-                    "lower framerate for songs with Live2D!");
-                deferredlogs::defer_error_messages({
-                    "Image Resize + SDVX Live2D performance warning",
-                    "    Enabling Image Resize feature is known to have significant impact",
-                    "    on Live2D performance; you should disable it"});
-            } else {
-                log_misc("ScreenResize", "enabled by config file");
-            }
+            log_misc("ScreenResize", "enabled by config file");
         }
 
         load_bool_value(doc, root + "enable_linear_filter", this->enable_linear_filter);