🐛 Audit mob_droplist table for unused or inaccurate entries

[claywar]

• [x] I have paid attention to this example and will edit again if need be to not break the formatting, or I will be ignored
• [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
• [x] I have read and understood the Contributing Guide

Branch affected by issue

base There are 46 unused drop Ids that are currently populated in the mob_droplist table. Need to figure out what these are for and correct.

Steps to reproduce

1. Search mob_droplist for 'Unknown' after #2109 is merged

Expected behavior

1. There should be no Unknown entries

[TeoTwawki]

bear in mind scripts can change a mobs drop list - it could be that (some of) these IDs are alternated used by script after some condition is met

related: https://github.com/LandSandBoat/server/issues/975