Enable DAST extra fields feature flag by default

What does this MR do?

enables security_dast_site_profiles_additional_fields feature flag by default.

Related Issue(s)

• #292897 (closed)

Documentation updates

• !59169 (merged)

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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