Enable maven CTE query optimization FF

What does this MR do?

This MR enables the maven_metadata_by_path_with_optimization_fence feature flag by default. The flag is already enabled on PRD.

• Rollout issue: #325460 (closed)
• Query performance issue: #325274 (comment 539947698)

Does this MR meet the acceptance criteria?

Conformity

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• Documentation (if required)
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• 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.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

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• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
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