fix(Scripts/Midsummer): fix handling of unwanted npc and gameobject s… (#19141)

fix(Scripts/Midsummer): fix handling of unwanted npc and gameobject spawns

- properly spawn bonfire spell focus for city bonfires
- properly despawn unwanted creatures and gameobjects which are spawned
  by linked traps
- all midsummer bonfire gameobjects have a linked trap "181290 Midsummer Bonfire Spawn Trap"
- the trap is linked to the spell "28784 Summon Midsummer Bonfire Bunnies" which then spawns
  npc "16592 Midsummer Bonfire", npc "16606 Midsummer Bonfire Despawner" and gameobject
  "181371 Midsummer Bonfire Spell Focus" i have no idea how this trap is beeing triggered,
  but it's doing only harm right now

data/sql/updates/pending_db_world/rev_1719166715720224400.sql

@@ -0,0 +1,5 @@
+-- 16606 'Midsummer Bonfire Despawner'
+-- add TRIGGER flag
+UPDATE `creature_template` SET `flags_extra` = (`flags_extra` | 128) WHERE (`entry` = 16606);
+-- Script
+UPDATE `creature_template` SET `ScriptName` = 'npc_midsummer_bonfire_despawner' WHERE (`entry` = 16606);