Downloaded update lost on quit, triggers re-download

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

* VS Code Version: 1.132.1
* Commit: c2d1b13fdc4a77628e5f3bb70173351c8f2fbad1
* Electron: 42.7.1
* OS Version: macOS (Darwin arm64 25.6.0)

### Steps to Reproduce:

1. Open VS Code and let it automatically download an available update.
2. Once the update is downloaded and the Update button is available, quit VS Code using Cmd+Q without clicking Update.
3. Reopen VS Code.
4. Click “Check for Updates”.

### Expected:

If the update package has already been downloaded, VS Code should detect and reuse it after reopening. It should show the Update button directly and install the existing package after verifying its integrity (e.g. checksum/hash), rather than downloading the same update again.

### Actual:

The downloaded update is not preserved correctly across a normal quit/relaunch. After reopening VS Code and checking for updates, it starts downloading the same update from scratch again.

https://github.com/microsoft/vscode/issues/303341. The issue is still present.