Fix Treasure Chest NPC ID reference in Pso'Xja IDs

[claywar]

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• I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
• I understand I should leave resolving conversations to the LandSandBoat team so that reviewers won't miss what was said.
• I have read and understood the Contributing Guide and the Code of Conduct.
• I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

What does this pull request do?

Pso'Xja has 6 mobs named treasure chest, and the 7th and last one is the NPC, in which GetFirstID would return the first mob. Pulls the entire table and sets to the last value for the expected NPC value, and to resolve the startup warning

Steps to test these changes

No warning, treasure chest NPC appears and works as expected

[Frankie-hz]

I was bound to miss one, thank you! I can go over all the treasure chest to see if I made that mistake somewhere else tonight.

[claywar]

At least for mobs, it appears that Pso'Xja is the only zone that has some named Treasure_Chest. There's a chance that other NPCs might be present though