fix: [stix2 import] More generic network-traffic references parsing
fix: [stix2 import] More generic network-traffic references parsing

- Also fixing some edge cases of reference parsing
  with the wrong mapping
  (network_traffic_references_mapping no longer exists)

MISP/MISP,MISP/MISP,SteveClement/MISP,MISP/MISP,MISP/MISP,SteveClement/MISP,SteveClement/MISP,MISP/MISP,SteveClement/MISP,SteveClement/MISP