fix(bluetooth): Split improvements

* Proper usage of bt_uuid_cmp.
* Central's don't start scanning for peripherals if
  `ZMK_BLE_CLEAR_BONDS_ON_START` is enabled.
* Split peripherals don't advertize if
  `ZMK_BLE_CLEAR_BONDS_ON_START` is enabled.

app/src/split/bluetooth/peripheral.c

@@ -116,11 +116,11 @@ static int zmk_peripheral_ble_init(const struct device *_arg) {
     LOG_WRN("Clearing all existing BLE bond information from the keyboard");
 
     bt_unpair(BT_ID_DEFAULT, NULL);
-#endif
-
+#else
     bt_conn_cb_register(&conn_callbacks);
 
     start_advertising();
+#endif
 
     return 0;
 }