Follow-up from "Resolve Tupling test running on spruced output" and " Remove old davinci configurable and related tests"

Follow up from !573 (merged) to be addressed:

• @sstahl started a discussion about
  • removing the unpacking function from the HltControlFlow
  • adding an Event prefilter (or something similar and more compatible with PyConf) in order to reduce the amount of time required by unpacking all the hlt locations
• @erodrigu started a discussion about
  • possibility to move the set_hltAnn_svc from DaVinci.algorithms to GaudiConf

Follow up from !568 (merged) to be addressed:

• @pkoppenb started a discussion about
  • maintaining the possibility to write .dst in DaVinci.