Ci fix: Fix reusable workflow loops, checkout refs, and workspace cleaning

[Jakio815]

This PR resolves critical issues in the CI workflow when called as a reusable workflow from iotauth:

• Avoid infinite loop triggers: Replaced github.event_name checks with inputs.iotauth-ref checks. (Since github.event_name inherits the caller's event name like push, the old condition did not prevent recursive calling).
• Correct checkout refs: Fixed checkout failures in called runs by ensuring Unit-Test checks out the correct sst-c-api ref instead of using the caller's (iotauth) commit SHA.

[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

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