mavlink_receiver: reduce s_variance_m_s for HIL GPS message from 1 to 0.1
mavlink_receiver: reduce s_variance_m_s for HIL GPS message from 1 to 0.1

1 was too high to pass the EKF2 test (EKF2_REQ_SACC which is 0.5 by default)
and thus switching into position mode in HIL was not possible.

acfloria/Firmware,Aerotenna/Firmware,mje-nz/PX4-Firmware,mje-nz/PX4-Firmware,PX4/Firmware,acfloria/Firmware,acfloria/Firmware,dagar/Firmware,mje-nz/PX4-Firmware,PX4/Firmware,PX4/Firmware,acfloria/Firmware,mje-nz/PX4-Firmware,PX4/Firmware,krbeverx/Firmware,krbeverx/Firmware,Aerotenna/Firmware,Aerotenna/Firmware,krbeverx/Firmware,dagar/Firmware,acfloria/Firmware,PX4/Firmware,dagar/Firmware,mje-nz/PX4-Firmware,mje-nz/PX4-Firmware,dagar/Firmware,krbeverx/Firmware,Aerotenna/Firmware,krbeverx/Firmware,dagar/Firmware,PX4/Firmware,acfloria/Firmware,PX4/Firmware,acfloria/Firmware,dagar/Firmware,mje-nz/PX4-Firmware,krbeverx/Firmware,dagar/Firmware,krbeverx/Firmware,Aerotenna/Firmware,Aerotenna/Firmware,Aerotenna/Firmware