Fix data decoding of BIS78 chambers

Hi everybody,

the BIS78 sMDT chambers are operated with HPTDC chips which are quite different from the legacy TDC chips. Nevertheless, the bytestream decode assumes to use the legacy format and hence the basic distributions of TDC and ADC just look nuts

This MR fixes the bytestream conversion of the sMDTs. The plots below show the ADC and TDC distributions after the fix

Tagging @dai

This MR is frozen-tier0-violating and also a super duper urgent bugfix. Let me tag @pberta, and @jmaurer to tell me how to proceed in terms of reference file updates as !54430 (merged) is currently also under review and needs a reference file update as well.