Disable the artefact subfolders entirely to simplify the report collection

[luhmirin-s]

Notable changes

• Adding merge-multiple: true flags disables the subfolder behaviour and extracts the contents into the test-reports folder directly.
• This in turn allows us to simplify collection down to a single "move" call since there are no more subfolders to deal with.

Additional work checklist

• Effect on other features and security has been considered
• Design document marked as "In development" (if applicable)
• External (Gitbook) and internal (Confluence) Documentation is up to date (or ticket created)
• Test cases in Testiny are up to date (or ticket created)
• Other teams notified about the changes (if applicable)

[Copilot]

Pull request overview

This PR simplifies how SonarQube scan workflows collect test reports by flattening downloaded artifacts into a single directory, eliminating per-artifact subfolders. This reduces the shell logic needed to gather reports before running Sonar.

Changes:

• Enable merge-multiple: true in the actions/download-artifact@v7 step so all artifact contents are downloaded directly into test-reports instead of per-artifact subdirectories.
• Replace the artifact-subfolder iteration and fallback logic with a single rsync -arv test-reports/* . || true call, relying on the flattened structure.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud