Fix S3 ArtifactStore auth issue

[avishniakov]

Describe changes

Fixes the authentication issued introduced with #3060

Pre-requisites

Please ensure you have done the following:

• I have read the CONTRIBUTING.md document.
• If my change requires a change to docs, I have updated the documentation accordingly.
• I have added tests to cover my changes.
• I have based my new branch on develop and the open PR is targeting develop. If your branch wasn't based on develop read Contribution guide on rebasing branch to develop.
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Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Other (add details above)

[avishniakov]

@stefannica I made the requested changes and tested this in different conditions: with new perms present or without for the legacy connector - all seems good. Shall we merge it? CI is a bit shaky, but I can merge it like this - there are only docker failures not related to the PR.