Privacy bits not getting set on Linux browser export

### Steps To Reproduce

Let's compare exports here on Linux,
```
-rw-r--r-- 1 402887 12-29 16:47 bitwarden_export_20231229164736.json
-rw------- 1 55302 12-29 16:44 Chrome Passwords.csv
```
We see Chrome exports passwords with group and world privacy bits turned
off (600 vs. 644.)

We are using the browser extension.

### Expected Result

Set the privacy bits upon save.

### Actual Result

Not set. Other users on the same machine can read the file.

### Screenshots or Videos

_No response_

### Additional Context

_No response_

### Operating System

Linux

### Operating System Version

_No response_

### Web Browser

Chrome

### Browser Version

121.0.6167.16
### Build Version

### Issue Tracking Info

- [X] I understand that work is tracked outside of Github. A PR will be linked to this issue should one be opened to address it, but Bitwarden doesn't use fields like "assigned", "milestone", or "project" to track progress.

No file or test is named. Start by tracing the Bitwarden browser extension's Linux export save flow and compare how it creates the JSON file with the reported Chrome export permissions. Done means exported files restrict group and world access as requested, with regression coverage for the Linux behavior.

Written by the indexing model from the issue text.