[Vanilla Bracket] - Engineering Schematics should be sold by the vendor and not trained

Issue: https://github.com/chromiecraft/chromiecraft/issues/6560

### What client do you play on?

enUS

### Faction

Both

### Content Phase:

Generic

### Current Behaviour

Engineering skills which should be learned through schematics were available via trainers
https://wowgaming.altervista.org/aowow/?spell=19795
https://wowgaming.altervista.org/aowow/?spell=19791

### Expected Blizzlike Behaviour

these crafting skills should not be available from trainers but require the schematic
https://www.wowhead.com/classic/item=16042/schematic-thorium-widget
https://www.wowhead.com/classic/item=16047/schematic-thorium-tube

### Source

.

### Steps to reproduce the problem

.

### Extra Notes

_No response_

### AC rev. hash/commit

https://github.com/chromiecraft/azerothcore-wotlk/commit/c863a8cfb59ed17692f9da2956b85a53ecc09ed7

### Operating system

Ubuntu 20.04

### Modules

- [mod-ah-bot](https://github.com/azerothcore/mod-ah-bot)
- [mod-bg-item-reward](https://github.com/azerothcore/mod-bg-item-reward)
- [mod-BreakingNewsOverride](https://github.com/AnchyDev/BreakingNewsOverride)
- [mod-cfbg](https://github.com/azerothcore/mod-cfbg)
- [mod-chat-transmitter](https://github.com/azerothcore/mod-chat-transmitter)
- [mod-cta-switch](https://github.com/azerothcore/mod-cta-switch)
- [mod-desertion-warnings](https://github.com/azerothcore/mod-desertion-warnings)
- [mod-duel-reset](https://github.com/azerothcore/mod-duel-reset)
- [mod-eluna](https://github.com/azerothcore/mod-eluna)
- [mod-instanced-worldbosses](https://github.com/nyeriah/mod-instanced-worldbosses)
- [mod-ip-tracker](https://github.com/azerothcore/mod-ip-tracker)
- [mod-low-level-arena](https://github.com/azerothcore/mod-low-level-arena)
- [mod-low-level-rbg](https://github.com/azerothcore/mod-low-level-rbg)
- [mod-multi-client-check](https://github.com/azerothcore/mod-multi-client-check)
- [mod-progression-system](https://github.com/azerothcore/mod-progression-system)
- [mod-pvp-titles](https://github.com/azerothcore/mod-pvp-titles)
- [mod-pvpstats-announcer](https://github.com/azerothcore/mod-pvpstats-announcer)
- [mod-queue-list-cache](https://github.com/azerothcore/mod-queue-list-cache)
- [mod-rdf-expansion](https://github.com/azerothcore/mod-rdf-expansion)
- [mod-transmog](https://github.com/azerothcore/mod-transmog)
- [mod-weekend-xp](https://github.com/azerothcore/mod-weekend-xp)
- [mod-zone-difficulty](https://github.com/azerothcore/mod-zone-difficulty)
- [lua-carbon-copy](https://github.com/55Honey/Acore_CarbonCopy)
- [lua-event-scripts](https://github.com/55Honey/Acore_eventScripts)
- [lua-exchange-npc](https://github.com/55Honey/Acore_ExchangeNpc)
- [lua-level-up-reward](https://github.com/55Honey/Acore_LevelUpReward)
- [lua-recruit-a-friend](https://github.com/55Honey/Acore_RecruitAFriend)
- [lua-send-and-bind](https://github.com/55Honey/Acore_SendAndBind)
- [lua-temp-announcements](https://github.com/55Honey/Acore_TempAnnouncements)
- [lua-zonecheck](https://github.com/55Honey/acore_Zonecheck)

### Customizations

None

### Server

ChromieCraft

Start by checking the trainer entries for spells 19795 and 19791 and the vendor data for items 16042 and 16047. Compare their current availability with the linked WoW references; done means the skills are no longer trainer-taught and the required schematics are sold by the appropriate vendor.

Written by the indexing model from the issue text.