Drop http_default_timeouts feature flag

What does this MR do?

• drop http_default_timeouts feature flag
• add changelog entry

Refs #233109 (closed)

Feature flag was enabled on 27th August, more information can be found here.

Screenshots

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.
• [-] Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done