fix(ble): Disable Auto Sec Req again.

* Auto security request actually makes macOS worse, so disable it,
  and remove our early request in favor of using GATT enforcement
 to ensure connections are secured.

app/Kconfig

@@ -144,7 +144,6 @@ if ZMK_BLE
 
 config ZMK_BLE_EXPERIMENTAL_CONN
     bool "Experimental BLE connection changes"
-    imply BT_GATT_AUTO_SEC_REQ
     help
       Enables a combination of settings that are planned to be default in future versions of ZMK
       to improve connection stability. This includes changes to timing on BLE pairing initation,

app/src/ble.c

@@ -447,12 +447,6 @@ static void connected(struct bt_conn *conn, uint8_t err) {
 
     LOG_DBG("Connected %s", addr);
 
-#if !IS_ENABLED(CONFIG_BT_GATT_AUTO_SEC_REQ)
-    if (bt_conn_set_security(conn, BT_SECURITY_L2)) {
-        LOG_ERR("Failed to set security");
-    }
-#endif // !IS_ENABLED(CONFIG_BT_GATT_AUTO_SEC_REQ)
-
     update_advertising();
 
     if (is_conn_active_profile(conn)) {