Change WinitPlugin defaults to limit game update rate when window is not visible (for real this time) (#11305)

# Objective

I goofed. #7611 forgot to change the default update modes set by the
`WinitPlugin`.


<ce5bae55f6/crates/bevy_winit/src/winit_config.rs (L53-L60)>


<ce5bae55f6/crates/bevy_winit/src/lib.rs (L127)>

## Solution

Change `Default` impl for `WinitSettings` to return the `game` settings
that limit FPS when the app runs in the background.

crates/bevy_winit/src/winit_config.rs

@@ -52,10 +52,7 @@ impl WinitSettings {
 
 impl Default for WinitSettings {
     fn default() -> Self {
-        WinitSettings {
-            focused_mode: UpdateMode::Continuous,
-            unfocused_mode: UpdateMode::Continuous,
-        }
+        WinitSettings::game()
     }
 }