Core/Auras: periodics refactor part 1:

- Don't skip ticks if diff is greater than amplitude
- Fixed spells without ampltude in DBC

(cherry picked from commit 5d91beb1dbc795382a12ec05f6e72c76b195b141)

src/server/scripts/Spells/spell_generic.cpp

@@ -1319,7 +1319,7 @@ class spell_gen_gift_of_naaru : public AuraScript
 
     void CalculateAmount(AuraEffect const* aurEff, int32& amount, bool& /*canBeRecalculated*/)
     {
-        if (!GetCaster())
+        if (!GetCaster() || !aurEff->GetTotalTicks())
             return;
 
         float heal = 0.0f;