This MR is meant to clean up the gFexDriver algorithm, and solve the error reported in ATR-28066, also discussed in !64533 (comment 7007367).
The m_gSuperCellTowerMapperTool that was wrongly called in the gFexDriver has now been removed, and there is no need to configure it in the L1CaloFEXSimCfg.py, anymore (removing Sergi's fix in !64938 (merged)).
Also, the gTowerContainer was wrongly saved to SG in both the gFEXDriver and the gTowerMakerFromGfexTowers. Now the container is only saved in gTowerMakerFromGfexTowers.
