Adjust Volume sliders defualt to 0 on cancel

### Testmerges

N/A

### Round ID

N/A

### Description of the bug

Opening the input box and then just hitting cancel or closing it without confirming an option will set it to 0

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

It shouldn't change anything if the user makes no changes

### How do we reproduce this bug?

1. Use one of the sliders
2. Exit or cancel without changing a number
3. You have now muted those sounds
...

### 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)