fix typo in DESDM_MCP output container

Patrick Scholer requested to merge pscholer/athena:fixDESDM_MCP into 23.0

Due to a typo we are not writing out any muon aux containers in the DESDM_MCP format. This MR fixes it. Adding urgent since without this fix no muon detector performance studies based on the DESDM_MCP format can be carried out. Tagging @jojungge @jmaurer @strichte

Edited by Patrick Scholer

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