fixed altitude estimator error estimation

[RomanLut]

ISSUE:

The signed difference is currently used to update the error estimation in the altitude estimator. A large negative difference incorrectly reduces the error, while it should actually increase the error.

Explanation: The difference gpsAltResudual should be passed through fabsf() to ensure that the error magnitude is always positive, preventing incorrect reduction of the error when the difference is negative.

IS:

const float gpsAltResudual = posEstimator.gps.pos.z - posEstimator.est.pos.z;
ctx->newEPV = updateEPE(posEstimator.est.epv, ctx->dt, MAX(posEstimator.gps.epv, gpsAltResudual), positionEstimationConfig()->w_z_gps_p);

SHOULD:

ctx->newEPV = updateEPE(posEstimator.est.epv, ctx->dt, MAX(posEstimator.gps.epv, fabsf(gpsAltResudual)), positionEstimationConfig()->w_z_gps_p);