Disable GameInput for mouse and keyboard by default

We're going to wait for this to get more testing before enabling it by default.

Fixes https://github.com/libsdl-org/SDL/issues/13846

include/SDL3/SDL_hints.h

@@ -4306,9 +4306,8 @@ extern "C" {
  *
  * The variable can be set to the following values:
  *
- * - "0": GameInput is not used for raw keyboard and mouse events.
+ * - "0": GameInput is not used for raw keyboard and mouse events. (default)
  * - "1": GameInput is used for raw keyboard and mouse events, if available.
- *   (default)
  *
  * This hint should be set before SDL is initialized.
  *