[NICLA] BLE notifications not working using mbed BLE stack

[trik]

Since BLE security feature is disabled, notifications and indications updates are not sent to central.

https://github.com/ARMmbed/mbed-os/blob/54e8693ef4ff7e025018094f290a1d5cf380941f/connectivity/FEATURE_BLE/source/cordio/source/GattServerImpl.cpp#L832