Build: Enable -Wimplicit-fallthrough on clang (#25056)

* Misc: Use [[fallthrough]] attribute instead of comment to mark intentional fallthroughs

Related: #25006

* Misc: Add some missing breaks (no-ops) to satisfy clang

Related: #25006
Closes #25055

* Build: Enable -Wimplicit-fallthrough on clang

Closes #25006

src/server/game/Spells/SpellEffects.cpp

@@ -1540,6 +1540,7 @@ void Spell::SendLoot(ObjectGuid guid, LootType loottype)
                     gameObjTarget->TriggeringLinkedGameObject(trapEntry, player);
 
                 // Don't return, let loots been taken
+                break;
             default:
                 break;
         }