Xenos can push crates.

### Testmerges

N/A

### Round ID

N/A

### Description of the bug

Xenos can push crates off to where-ever.
This has already been deemed an Exploit by management.
But I might as well put it here with the funny label for the 3 people that search for these things

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

They don't get to push the crate to Narnia, and hide them

### How do we reproduce this bug?

1. Be evil xeno
2. Walk into a crate
3. It gets pushed by evil physics
...

### 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)

Start by reproducing the issue in a recent round with an evil xeno walking into a crate, as described in the report. Trace the crate-pushing behavior from the xeno movement interaction and verify that crates can no longer be pushed away or hidden by xenos.

Written by the indexing model from the issue text.