Take fuel warning level percent from telemetry data

[avengerx]

Telemetry data provides fuel warning level percent value from SCS_TELEMETRY_CONFIG_ATTRIBUTE_fuel_warning_factor; a value between 0.00 and 1.00, usually 0.15. Use this value instead of a fixed 0.15 to adapt to different truck values if there are any, allowing the gauge to be more consistent across different trucks and have the red leds right when the fuel warning actually lights up.