[lua] Various PH Fixes

[KiplingFFXI]

I affirm:

• 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?

This PR adds placeholders to NMs that didn't have them, fixes a bug with Vilma and Taisaijin, and does some general NM cleanup.

• Adds spawn points to Ancient Goobbue, Juggler Hecatomb, and Oni Carcass.
• Refines spawn points for Argus and Leech King. Removes the duplicate Argus/Leech King init roll from Argus.lua because Zone.lua's onInitialize already does this.
• Corrects Soulstealer Skullnix's placeholders to the two real ones (Goblin Alchemist and Goblin Bandit).
• Fixes a bug in Voluptuous Vilma's onMobDespawn due to referencing a nil value.
• Fixes a bug in Taisaijin's onMobDespawn when he spawns outside the grow system and has no phIndex set.
• Makes Taisaijin grow at his placeholder's position instead of his fixed spawn point.

Steps to test these changes

!spawnmob the above mobs and witness the changes.