QuestieArrow._CollectObjective was only checking objective.Completed
to determine if it should skip an objective. In WotLK, the server often
doesn't send the completed flag until turn-in time.
This caused the arrow to still pick up the kill/interaction spawns (like
the 5/5 Goblin Prisoners) because their Completed flag hadn't been
set, overpowering the finisher spawn.
Added a fallback check: if objective.Collected >= objective.Needed,
skip the objective.
Xurkon