For #26692 (fixes permission issue when extracting dirs).
Reverts changes to `update.go` to remove TUF test surface.
# Checklist for submitter
If some of the following don't apply, delete the relevant line.
<!-- Note that API documentation changes are now addressed by the
product design team. -->
- [x] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements)
- [x] A detailed QA plan exists on the associated ticket (if it isn't
there, work with the product group's QA engineer to add it)
- [x] Manual QA for all new/changed functionality
- For Orbit and Fleet Desktop changes:
- [ ] Make sure fleetd is compatible with the latest released version of
Fleet (see [Must
rule](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/fleetd-development-and-release-strategy.md)).
- [ ] Orbit runs on macOS, Linux and Windows. Check if the orbit
feature/bugfix should only apply to one platform (`runtime.GOOS`).
- [ ] Manual QA must be performed in the three main OSs, macOS, Windows
and Linux.
- [ ] Auto-update manual QA, from released version of component to new
version (see [tools/tuf/test](../tools/tuf/test/README.md)).