A client's "regenerate keys" action sends a blank SecurityConfig carrying
only the new private key rather than the config it read from the device,
so assigning it wholesale cleared admin_key, is_managed, serial_enabled,
debug_log_api_enabled, admin_channel_enabled and packet_signature_policy.
Losing the admin keys locks the owner out of remote admin with no recourse
but a physical connection to the node.
Detect that bare-rotation shape and swap in just the keypair, leaving the
rest of the security config intact. Deliberately clearing admin keys still
works through a SET that leaves the private key alone.
Fixes#11073
Ben MeadorsandGitHub
5cf346311c