Revert "Merge pull request #16483 from Treeston/3.3.5-debuffimmunity"…

… to fix #16589 while I investigate the retail behavior of SPELL_ATTR_0_UNAFFECTED_BY_INVULERABILITY further.

This reverts commit d67e877, reversing
changes made to cfed2d7.

(cherry picked from commit 26bbba4)

src/server/game/Spells/Auras/SpellAuraEffects.cpp

@@ -3568,7 +3568,7 @@ void AuraEffect::HandleAuraModSchoolImmunity(AuraApplication const* aurApp, uint
                 && !iter->second->IsPositive()          //Don't remove positive spells
                 && spell->Id != GetId())               //Don't remove self
             {
-                target->RemoveAura(iter, AURA_REMOVE_BY_ENEMY_SPELL);
+                target->RemoveAura(iter);
             }
             else
                 ++iter;

src/server/game/Spells/SpellInfo.cpp

@@ -1583,18 +1583,14 @@ bool SpellInfo::CanDispelAura(SpellInfo const* aura) const
     if (Attributes & SPELL_ATTR0_UNAFFECTED_BY_INVULNERABILITY && !aura->IsDeathPersistent())
         return true;
 
-    // These auras (Cyclone for example) are not dispelable
-    if (aura->HasAttribute(SPELL_ATTR1_UNAFFECTED_BY_SCHOOL_IMMUNE))
-        return false;
-
-    // Divine Shield etc can dispel auras if they don't ignore school immunity
-    if (HasAttribute(SPELL_ATTR1_DISPEL_AURAS_ON_IMMUNITY) && !aura->IsDeathPersistent())
-        return true;
-
     // These auras (like Divine Shield) can't be dispelled
     if (aura->HasAttribute(SPELL_ATTR0_UNAFFECTED_BY_INVULNERABILITY))
         return false;
 
+    // These auras (Cyclone for example) are not dispelable
+    if (aura->HasAttribute(SPELL_ATTR1_UNAFFECTED_BY_SCHOOL_IMMUNE))
+        return false;
+
     return true;
 }