Fake zombie used for spawning. I saw that and create an issue.

### Describe the bug

I saw a dummy zombie for spawn another zombie in strange place, which not a mass grave. Just a field.

### Attach save file

[2024-trimmed.tar.gz](https://github.com/CleverRaven/Cataclysm-DDA/files/13853829/2024-trimmed.tar.gz)

### Steps to reproduce

find similar place to what is in the save file. I do not know if this compares to normal mass graves or cemeteries. At least I haven't seen it.

### Expected behavior

Dummy zombie must not be shown to the player.

### Screenshots


### Versions and configuration

Windows 10, CDDA build 2024-01-07-0753
[debug.log](https://github.com/CleverRaven/Cataclysm-DDA/files/13853830/debug.log)

### Additional context

_No response_

Start by loading the attached 2024-trimmed.tar.gz save file and reviewing debug.log, then compare the reported field with normal mass graves and cemeteries. Trace the zombie-spawning behavior from the reproduced location; done means the dummy zombie is no longer visible to the player while valid spawned zombies still appear.

Written by the indexing model from the issue text.