Disables rgblight twinkle by default. (#13677)

This takes up about 700 bytes of space, and needs to be swapped to
opt-in, rather than opt-out. Build failures in general on AVR due to the
scarcity of available flash. People can re-enable it by adding to their
keymap's config.h files:

```
  #define RGBLIGHT_EFFECT_TWINKLE
```

quantum/rgblight/rgblight.h

@@ -79,7 +79,6 @@
 #    define RGBLIGHT_EFFECT_STATIC_GRADIENT
 #    define RGBLIGHT_EFFECT_RGB_TEST
 #    define RGBLIGHT_EFFECT_ALTERNATING
-#    define RGBLIGHT_EFFECT_TWINKLE
 #endif
 
 #ifdef RGBLIGHT_STATIC_PATTERNS