Remove ignore_column from Ci::JobArtifact

What does this MR do?

Removes ignore_columns :locked from Ci::JobArtifact

Related #244466 (closed)

Does this MR meet the acceptance criteria?

Conformity

• N/A Changelog entry
• N/A Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• N/A Database guides
• N/A Separation of EE specific content