Core/Pet: load template immunities when creating (except for hunters)

Fixes #19275

(cherry picked from commit e33263c677)

src/server/game/Entities/Pet/Pet.cpp

@@ -375,6 +375,8 @@ bool Pet::LoadPetFromDB(Player* owner, uint32 petEntry, uint32 petnumber, bool c
     if (owner->GetTypeId() == TYPEID_PLAYER && isControlled() && !isTemporarySummoned() && (getPetType() == SUMMON_PET || getPetType() == HUNTER_PET))
         owner->ToPlayer()->SetLastPetNumber(petId);
 
+    // must be after SetMinion (owner guid check)
+    LoadMechanicTemplateImmunity();
     m_loading = false;
 
     return true;