Draft: Bump to AthAnalysis 25.2.68 and Athena 25.0.42

This release bump is a bit nasty because a lot of changes in Athena broke things here, and fixing some of that requires further changes in Athena.

Partial list of things we're working around here:

• The changes in atlas/athena!80818 (merged) (dropping the code to tag BTagging). I managed to get a legacy configuration working by moving a lot of the GNN code to tag the Jet rather than the BTagging object.
• Retagging needs to be adjusted: BTagAlgsCfg has been replaced by FlavorTaggingCfg
• ATLASG-2948: there were several releases where PathResolver was broken in containers.
• In the meantime barcode was removed, which requires either atlas/athena!82746 (merged) (Attila's comprehensive fix) or atlas/athena!82558 (my workaround).
• Something in the CP Algorithms broke in the meantime (I saw a segfault but didn't look further)
• The base release will have to be bumped up whatever comes after 25.2.64 (and probably after 25.0.41) to get all the fixes above.

I (Alex) took over from here. We cannot fix all of the mentioned stuff, so I will document everything from the not finished tasks above here.

• Retagging: Retagging is a bit more broken than expected and needs a bit more changes. I put the unit tests for now to allow_fail: true. I think once this is merged, @anburger will work on this in !931 (Reminder: remove allow_fail once retagging works again). PLEASE TAG THE CODE BEFORE MERGING THIS MR!
• Some CP algorithm issues in the FTAG2 pipeline are fixed (MC). The segfault in the data jobs seem to arise again from an issue in Pathfinder that might be fixed by atlas/athena!82272.
• The base release is set to 25.2.68 (AthAnalysis) and 25.0.42 (Athena) to get all the fixes in