Damage in limbs get removed once de-limbed

### Testmerges

dnm

### Round ID

dnm

### Description of the bug

All the damage in a limb gets removed from a mob once you are delimbed, meaning you get healed in certain cases

### What's the difference with what should have happened?

should probably keep the damage

### How do we reproduce this bug?

1.delimb somebody
2.watch total health go up
3.
...

### Issue Bingo

- [x] Issue could be reproduced at least once
- [x] Issue happened in a recent (less than 7 days ago) round
- [x] Couldn't find an existing issue about this (https://github.com/cmss13-devs/cmss13/issues)