Eggs can be dropped while vent crawling

## Testmerges
#7023: 'Research Rework Part Two: The Contract System.' by kiVts at commit dd2764717f
#7242: 'WIP Yautja Clan TGUI Menu' by realforest2001 at commit ba93dc064c
#9274: 'introduces two factor authentication for admins' by hry-gh at commit 4e4d947553
#9099: 'replaces smartgunner auto fire with aim assist' by jupyterkat at commit e0f339fb04
#9254: 'disables cade anchoring on the almayer, alternative to #9144' by psyendrocronologicalwarfare at commit 0d11c82f81
#9286: 'fixes an attachment bug' by Detective-Google at commit a34219c08d
#9293: 'FOB Defense Rework' by Git-Nivrak at commit ab2caae3bb
#9384: 'Gibs player huggers on ghost' by Git-Nivrak at commit dd096b6fb7
#9390: 'fix clf surv skills' by BOBAMAx at commit 0bd7eaa16e
#9405: '[EVENT] Pathogen Confluence' by realforest2001 at commit 439a429883

## Round ID
28110

## Description of the bug
Drone can drop an unplanted egg while crawling through vents, making the egg pop out on the same tile on the ground for everyone to pick it up.
Same with picked up gardener gruits.
Lesser drones probably can do it too, but I didn't checked.

## What's the difference with what should have happened?
Drone can't drop any held items while in vents.

## How do we reproduce this bug?
1. Pick up an unplanted egg as a drone
2. Use "Crawl through Vent" in the "Alien" tab to enter any vent
3. Drop the held egg

## Attached logs
```
N/A
```

## Additional details
- Author: Veglok
- Admin: Stalkerino
- Note: None

Start by reproducing the issue with an unplanted egg or gardener gruit: enter a vent through the Alien tab's "Crawl through Vent" action, then drop the held item. Trace the vent-crawling and item-drop entry points; done means drones and lesser drones cannot drop held items while inside vents, with the behavior checked in-game.

Written by the indexing model from the issue text.