The `_deadreckon_time_exceeded` flag is used in
`local_position_is_valid()`. This means that
`_params.valid_timeout_max` after startup, in my observed case 5
seconds, the local position switche from valid to invalid and then after
a while back to valid again.
With this fix, the local position is flagged invalid from boot and gets validated after the first aiding event.
Co-authored-by: Julian Oes <julian@oes.ch>