Core/Spell: don't set scaleAura for some special spells

Closes #14541

(cherry picked from commit 1ca8434b365687dbd12ca232a615d126234eba5e)

src/server/game/Spells/SpellInfo.cpp

@@ -3851,6 +3851,10 @@ bool SpellInfo::_IsPositiveEffect(uint8 effIndex, bool deep) const
     if (HasAttribute(SPELL_ATTR0_NEGATIVE_1))
         return false;
 
+    // these spells must not be downscaled, thus marking them negative (see GetAuraRankForLevel)
+    if (HasAttribute(SPELL_ATTR2_UNK3))
+        return false;
+
     switch (SpellFamilyName)
     {
         case SPELLFAMILY_GENERIC: