yaw_reset: reduce minimum vector length to compute yaw error
yaw_reset: reduce minimum vector length to compute yaw error

A value of 1m/s was too conservative and the EKF takes too much time to
trigger a yaw reset. The value can be safely reduced because the
threshold is computed using the accuracy of the measurement and estimate
before being limited by this value.

PX4/ecl,PX4/ecl,PX4/ecl,PX4/ecl,PX4/ecl