CLI-1171: Home directory errors on Windows

[Jura]

Motivation

Fixes #1610

Proposed changes

extending env variable testing condition to avoid PHP error when the var is not present

Alternatives considered

Testing steps

1. Follow the contribution guide to set up your development environment or download a pre-built acli.phar for this PR.
2. Clear the kernel cache to pick up new and changed commands: ./bin/acli ckc
3. (add specific steps for this pr)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (5fdac94) 91.68% compared to head (1bd01cb) 91.78%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1611 +/- ## ============================================ + Coverage 91.68% 91.78% +0.09% Complexity 1809 1809 ============================================ Files 124 124 Lines 6485 6485 ============================================ + Hits 5946 5952 +6 + Misses 539 533 -6 ``` | [Files](https://app.codecov.io/gh/acquia/cli/pull/1611?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=acquia) | Coverage Δ | | |---|---|---| | [src/Helpers/LocalMachineHelper.php](https://app.codecov.io/gh/acquia/cli/pull/1611?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=acquia#diff-c3JjL0hlbHBlcnMvTG9jYWxNYWNoaW5lSGVscGVyLnBocA==) | `62.22% <100.00%> (+4.44%)` | :arrow_up: |

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[Jura]

Thanks @danepowell, I couldn't cherry pick from the fork you referenced (insufficient permissions) so transferred changes manually. If you want to keep your name on the commit - we can reverse it and you could commit to my fork, I added yo as a contributor to https://github.com/undp/acquia-cli