Oldchat colors broken

### Testmerges

irrelevant

### Round ID

irrelevant

### Description of the bug

Formatting is lost if you use oldchat for some reason. For example hivemind is not purple. It was not a problem few months ago. I know no one cares about oldchat but tgui lags a lot for me so I use oldchat. pls fix.

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

Text should have appropriate formatting.

### How do we reproduce this bug?

1. Use fix chat verb
2. Switch to old UI (might need several attempts for it to proc)
3. See text lacking formatting.

### 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)