🐛 [battlefield] Correct addEssentialMobs armoury crate search when area = 1

[claywar]

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• [x] I understand that if I do not agree to the following points by completing the checkboxes my issue will be ignored.
• [x] I have read and understood the Contributing Guide and the Code of Conduct.
• [x] I have searched existing issues to see if the issue has already been opened, and I have checked the commit log to see if the issue has been resolved since my server was last updated.

OS / platform the server is running (if known)

Branch affected by issue

base

Steps to reproduce

1. Enter Ghelsba Outpost -> Wings of Fury (without armouryCrates variable defined)
2. Win Battlefield

Expected behavior

addEssentialMobs should set armoury crate appropriately based on NPC list, but return is 0. This only appears to occur when there is one battlefield area available (not to be confused with allowedAreas where there are multiple, but restricted)