Fix condition for uploading artifacts in worker.yml

[Akshat-Jain]

Description

The if: ${{ failure() }} || ${{ inputs.artifact_prefix != '' }} condition in always seems to be evaluating to true, as can be seen here where the upload artifact step was run even though no prior step failed: https://github.com/implydata/druid/actions/runs/13199722965/job/36850130824?pr=3053

This is also the reason why this job failed on the weekly cron: https://github.com/apache/druid/actions/runs/13211720628/job/36886496050

This PR fixes it.

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This PR has:

• been self-reviewed.
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.