Fix MuonEventTPCnv_CscPrepDataContainerCnv_p2_test in 21.3
Hi,
to fix the MuonEventTPCnv_CscPrepDataContainerCnv_p2_test in 21.3, also the get_detectorElement_hash function of CSCs needs a fallback for (non-existing) chamberLayer=1 CSC chambers.
Tagging @jchapman who was interested in that fix.
Best, Nico