Validate that unprivileged installation works with Windows Active Directory

## Overview

Validation needs to be performed to ensure that the unprivileged mode installation works with a Windows machine that is enrolled into Active Directory.

### Test 1

The first test just needs to use the standard `--unprivileged` flag when installing and keep the defaults. That should create the standard local users for the Elastic Agent to run unprivileged.

Validate the following:

- [ ] Service is installed with the correct run as users
- [ ] User is created
- [ ] Group is created
- [ ] Runs correctly

### Test 2

The second test needs to use the `--user`, `--password`, and `--group` to install unprivileged where the `--user` and `--group` should be Active Directory users and groups.

Validate the following:

- [ ] Service is installed with run as --user
- [ ] User is not created (existing user used for --user)
- [ ] Group is not created (existing group used for --group)
- [ ] Runs correctly