Z level Fireman carry

## Testmerges
#9894: 'Multiz indicator' by Detective-Google at commit 5dbc10a0d2
#7093: 'creates ipcheck subsystem' by hry-gh at commit 83b2e4a403
#10340: 'New on_mobs for splints, bandages and blood overlays (Other changes to blood included)' by LC4492 at commit 14a671a4e4
#10830: 'cm-live' by hry-gh at commit f24923be15
#8963: 'Ports tacmap port from PVE' by Git-Nivrak at commit 167824715d
#10536: 'Tailstabs cross Z & Tailstab behavior for most obj/structures' by Drulikar at commit 70af72e2ac
#10845: 'Repeated Tackle Stun Resistance' by Drulikar at commit f0aa4e0542

## Round ID
30373

## Description of the bug
Going down Z-levels by climbing down while fireman carrying leaves the person you are carrying behind.

## What's the difference with what should have happened?
Not to leave them behind.

## How do we reproduce this bug?
1. Fireman Carry
2. Climb down Z level by left clicking open space
3. They are still up there.

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

## Additional details
- Author: 0nemore
- Admin: Westrover
- Note: None