Improve watch_tcc to decouple leds and buzzer as much as allowed

As a positive side effect, the led will stop emitting the faintiest
of blinks when the buzzer starts playing.

watch-library/simulator/watch/watch.c

@@ -1,9 +1,5 @@
 #include "watch.h"
 
-bool watch_is_buzzer_or_led_enabled(void) {
-    return false;
-}
-
 bool watch_is_usb_enabled(void) {
     return true;
 }