Cleaning as part of resolving ATLASRECTS-4365 from FTAG area.
This MR delete the CalibrationBroker tool and its clients as discussed in the ticket and during last SW FTAG meeting with @filthaut, @dguest et al.
CalibrationDataInterfaceROOT is the main (low-level) interface used now.
Tagging: @vdao @biliu @thuffman @pgadow @mguth @anburger @alopezso for awarness