Fix gitlab:cleanup:orphan_job_artifact_files rake task limit

What does this MR do?

Methods should not be defined in rake files https://kevinjalbert.com/defined_methods-in-rake-tasks-you-re-gonna-have-a-bad-time/

The limit method was defined in a new rake task, so the old one became overridden. The new method had a default of 100.

This MR also renames the newer method more specifically, since it would be a larger refactor to remove the method entirely.

Resolves #263415 (closed)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
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Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.