Core/Spells: Remove incorrect usage of SPELL_ATTR0_NEGATIVE_1 in CanDispelAura (which is used in SPELL_AURA_SCHOOL_IMMUNITY handling)

Closes #5940

src/server/game/Spells/SpellInfo.cpp

@@ -1127,10 +1127,6 @@ bool SpellInfo::CanPierceImmuneAura(SpellInfo const* aura) const
 
 bool SpellInfo::CanDispelAura(SpellInfo const* aura) const
 {
-    // These auras (like ressurection sickness) can't be dispelled
-    if (aura->Attributes & SPELL_ATTR0_NEGATIVE_1)
-        return false;
-
     // These spells (like Mass Dispel) can dispell all auras
     if (Attributes & SPELL_ATTR0_UNAFFECTED_BY_INVULNERABILITY)
         return true;