Core/Mechanics: Fix prevent fleeing + fear

Closes #9754

Players should never have been affected by SPELL_AURA_PREVENTS_FLEEING in the first place.
Curse of Recklessness will no longer prevent Fear effects, only prevent NPCs from fleeing (e.g. at low health).
Judgement of Justice will no longer prevent Fear effects, but will only prevent NPCs from fleeing (e.g. at low health).
Source: http://www.wowwiki.com/Patch_3.0.2
Merge pull request #13140 from Unholychick/preventfleeing

Core/Mechanics: Fix prevent fleeing + fear