VS Code Snap leaves processes running after exit and blocks updates

Does this issue occur when all extensions are disabled?: Yes

- VS Code Version: 1.134.0 (Snap revision 258)
- OS Version: Ubuntu 24.04.4 LTS, amd64, X11

* Installation: official `code` Snap, `latest/stable`, classic confinement

### Steps to Reproduce:

1. Ensure no stale VS Code Snap scope is running.
2. Launch VS Code with all extensions disabled:

code --disable-extensions

3. Close VS Code normally.
4. Run:

systemctl --user list-units 'snap.code.code-*.scope'

5. Run:

pgrep -af 'chrome_crashpad_handler|dconf watch /system/proxy/'

### Actual behavior:

After VS Code 1.134.0 (Snap revision 258) was launched with
`code --disable-extensions` and then closed normally, its Snap scope
remained active:

snap.code.code-d8bde8df-5c41-445b-9f80-f2322684d880.scope
loaded active running

The following VS Code-related processes also remained:

17000 /snap/code/258/usr/share/code/chrome_crashpad_handler ...
17204 dconf watch /system/proxy/

Both chrome_crashpad_handler and dconf watch /system/proxy/ remain in the active snap.code.code-*.scope after VS Code exits.

Therefore this reproduces with all extensions disabled.

When a Snap update is pending, these surviving processes cause snapd to
consider VS Code still running and postpone/refuse the refresh.

Stopping the stale snap.code.code-*.scope manually allows the pending
refresh to proceed.

### Expected behavior

After the last VS Code window is closed, VS Code-related helper processes should terminate and the `snap.code.code-*.scope` should disappear, allowing snapd to refresh VS Code normally.

### Workaround

Stopping the stale scope allows the pending update to proceed immediately:

```bash
systemctl --user list-units --type=scope --state=running --no-legend 'snap.code.code-*.scope' \
| awk '{print $1}' \
| xargs -r systemctl --user stop
```

After doing this, the pending VS Code Snap update completes successfully.

This has reproduced across multiple VS Code Snap revisions.