report exist trait exception

as the placement only accept the traits that with "CUSTOM_" prefix, when we report the "OWNER_" prefix trait, the cyborg-conductor will raise excetpion below:
Failed to add device DriverDevice(controlpath_id=DriverControlPathID,created_at=<?>,deployable_list=[DriverDeployable],model='NVIDIA Corporation GV100GL [Tesla V100 PCIe 3
2GB]',std_board_info='{"product_id": "1db6", "controller": "3D controller"}',stub=False,type='GPU',updated_at=<?>,vendor='10de',vendor_board_info='{"device_address": "0000:86:00.0", "vgpu_type": null}'). Reason: Failed to create trait OWNER_CYBORG: HTTP 400: {"errors": [{"status": 400,
"title": "Bad Request", "detail": "The server could not comply with the request since it is either malformed or otherwise incorrect.\n\n The trait is invalid. A valid trait must be no longer than 255 characters, start with the prefix \"CUSTOM_\" and use following characters: \"A\"-\"Z\"
, \"0\"-\"9\" and \"_\" ", "request_id": "req-0cf3985a-d054-4d0b-b7a2-adfd428401dc"}]}