refactor(Core/Unit): minor changes for the combat system (#11904)

Cherry-pick from TC: https://github.com/TrinityCore/TrinityCore/pull/19966

Co-authored-by: Treeston <treeston.nmoc@gmail.com>

src/server/game/Spells/SpellEffects.cpp

@@ -2677,7 +2677,7 @@ void Spell::EffectDistract(SpellEffIndex /*effIndex*/)
         return;
 
     // Check for possible target
-    if (!unitTarget || unitTarget->IsInCombat())
+    if (!unitTarget || unitTarget->IsEngaged())
         return;
 
     // target must be OK to do this