[Simulation] EMEC simulation AF3 in G4 (split thresholds for e and y and update default config)

Rui Zhangrequested to merge
zhangr/athena:rui_emec_study_24.0.79 into 24.0

A few updates was missed by git merge in MR !78027 (merged).

Tagging simulation conveners @schaarsc @mbandier and FCS convener @jbeirer.

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