Remove sTGC hits with negative calibrated charge

sTGC calibrated charge in data may become negative due to the lack of proper calibration constants. The negative charges are removed to prevent errors downstream. They represent a small fraction of hits that have low deposited energy, so discarding them would have a negligible impact. With proper calibration, all charge values should be positive.

This merge request targets ATLASRECTS-714, restoring some changes by @sangelid to protect against corrupted data !55062 (closed). Tagging also @pscholer, @jojungge, @rosati