Remove `ci_update_queues_for_online_runners` ff

What does this MR do?

Related to: #251080 (closed)

Removes already enabled feature flag.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content