CAS UI defaults targets, making recently melted flares bait for FF

[IsProbablyCatto]

Testmerges

#4475, #4812, #4793, #4866, #4863, #4872

Round ID

19433

Description of the bug

When lases are dropped or flares melt out, the UI defaults to a new flare which causes great FF moments when your flare burns out just as you hit fire.

What's the difference with what should have happened?

Just don't target anything at all, good reason why old UI defaulted to untargetted

How do we reproduce this bug?

1. Target a flare or lase
2. Remove the target
3. UI defaults to new target
   ...

Issue Bingo

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