Remove jira_sync_builds feature flag [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

Enables the feature to sync builds to Jira.

See: #292013 (closed)

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

Availability and Testing

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

Related to #292013 (closed)