Only trigger encoder callbacks on primary side (#18467)

Co-authored-by: zvecr <git@zvecr.com>

quantum/encoder/tests/mock.c

@@ -34,3 +34,7 @@ bool setPin(pin_t pin, bool val) {
     pins[pin] = val;
     return val;
 }
+
+__attribute__((weak)) bool is_keyboard_master(void) {
+    return true;
+}