Update creation of SubRun transition Fragments

[eflumerf]

Outdated code is here:
https://github.com/Mu2e/otsdaq_mu2e_calorimeter/blob/d3bb35719ffd2c54fa464d03fe02fbae20a854ce/otsdaq-mu2e-calorimeter/Generators/Mu2eCaloEventReceiver_generator.cc#L81
And here:
https://github.com/Mu2e/otsdaq_mu2e_calorimeter/blob/develop/otsdaq-mu2e-calorimeter/Generators/CalorimeterVST_generator.cc#L857

And should be replaced with code that looks like this:
https://github.com/Mu2e/artdaq_mu2e/blob/develop/artdaq-mu2e/Generators/Mu2eSubEventReceiver_generator.cc#L120-L124

[normanajn]

Can you verify that this was done.