remove sport=safety_training

[Klumbumbus]

sport=safety_training is part of the internal preset, but its meaning is unclear.

• In JOSM it is located in sport -> motorsport with this icon: , so it suggests that its meaning is vehicle driving safety training (in germany often offered at raceways), where you learn how to correctly react in critical driving situations like aquaplaning.
• in the osm wiki it is only on the page ​Key:sport
  • there is a link to a totally unrelated wiki page
  • the description sounds like training for self defense
  • the image looks like workplace health and safety traning
• the poll I created gives a unclear result

So I'm going to remove this tag from the internal preset until the definition is clear.