RFR: 8342609: jpackage test helper function incorrectly removes a directory instead of its contents only

[Alexander Matveev]

On Fri, 18 Oct 2024 13:45:00 GMT, Alexey Semenyuk <asemenyuk at openjdk.org> wrote:

> `Files.walk(root, 0)` returns the `root` itself and not the contents of the `root`.
> Replaced `Files.walk(root, 0)` with `Files.list(root)` to get a non-recursive listing of the `root` directory.

Marked as reviewed by almatvee (Reviewer).

-------------

PR Review: https://git.openjdk.org/jdk/pull/21582#pullrequestreview-2383379068