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
```
Nick Brassel