fix: ensure we do not get gcloud user during on-prem builds where GCP…

[jsilva]

Describe your changes

This PR adds a fix to ensure we do not get gcloud user during on-prem builds where GCP access is not allowed.

Issue ticket number and link

N/A

Checklist before requesting a review

• [x] I have performed a self-review of my code
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [ ] If it is a core feature, I have added thorough tests.

[codecov-commenter]

Codecov Report

Base: 74.20% // Head: 74.15% // Decreases project coverage by -0.06% :warning:

Coverage data is based on head (300876e) compared to base (fa0fa3e). Patch coverage: 0.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #79 +/- ## ========================================== - Coverage 74.20% 74.15% -0.06% ========================================== Files 57 57 Lines 2749 2751 +2 ========================================== Hits 2040 2040 - Misses 709 711 +2 ``` | [Impacted Files](https://codecov.io/gh/avast/wanna-ml/pull/79?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=avast) | Coverage Δ | | |---|---|---| | [src/wanna/core/utils/credentials.py](https://codecov.io/gh/avast/wanna-ml/pull/79?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=avast#diff-c3JjL3dhbm5hL2NvcmUvdXRpbHMvY3JlZGVudGlhbHMucHk=) | `64.51% <0.00%> (-4.45%)` | :arrow_down: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=avast). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=avast)

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