fix: Corrected attribute degradation on pull
fix: Corrected attribute degradation on pull

- events were correctly degrading, however, attributes weren't on a pull
- also removed some ancient compatibility code that was there for MISP 2.0 which is a version that hasn't been supported in ~3 years

crruthe/MISP,FIRSTdotorg/MISP,MISP/MISP,devnull-/MISP,crruthe/MISP,devnull-/MISP,Rafiot/MISP,SteveClement/MISP,FIRSTdotorg/MISP,FloatingGhost/MISP,FloatingGhost/MISP,Rafiot/MISP,cristianbell/MISP,Rafiot/MISP,MISP/MISP,FloatingGhost/MISP,MISP/MISP,crruthe/MISP,cristianbell/MISP,FIRSTdotorg/MISP,SteveClement/MISP,crruthe/MISP,SteveClement/MISP,SteveClement/MISP,TheDr1ver/MISP,FloatingGhost/MISP,devnull-/MISP,FIRSTdotorg/MISP,SteveClement/MISP,MISP/MISP,TheDr1ver/MISP,Rafiot/MISP,TheDr1ver/MISP,cristianbell/MISP,TheDr1ver/MISP,devnull-/MISP,cristianbell/MISP,MISP/MISP