Disease icon shows up as dead icon for xenos.

## Testmerges
#10830: 'CMLIVE!™️' by hry-gh at commit 858d10d4d6
#10883: 'Blocks tiles you cannot view while looking up' by Git-Nivrak at commit 5d0d58b9f6
#10926: 'Medals Overhaul' by realforest2001 at commit 7df4ad80f9
#10999: 'Fix of various plane related issues' by Blundir at commit f85a7153c4
#10964: 'Fixes for negative power and APC polish' by Drulikar at commit cfebf58f27
#11024: 'Announcement garble w/o coms and stars_decode_html fix' by Drulikar at commit 922b12594f
#10937: 'Various deconstruction do_after exploit fixes and cleanup' by Drulikar at commit 1c988dda9a
#11099: 'Fix MD and QuadTrees' by Drulikar at commit 54694a0eeb
#10376: 'CIA Overhaul' by realforest2001 at commit 48caf2f24f

## Round ID
30876

## Description of the bug
When xenos look at someone with a disease, it shows up as the usual skull icon that they see when a human dies, instead of the disease icon, or nothing at all.

## What's the difference with what should have happened?
xenos should not see the disease icon as a dead icon

## How do we reproduce this bug?
1. be a xeno
2. see a diseased marine
3. disease icon shows up as a skull

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

## Additional details
- Author: SmellyHippie
- Admin: SmellyHippie
- Note: None

Start by reproducing the issue as a xeno observing a diseased marine, then trace the disease and death-icon handling involved in that view. Done means the disease is no longer rendered as the skull icon for xenos, either by showing the correct disease icon or by showing no icon.

Written by the indexing model from the issue text.