WIP: Enable keyset pagination by default

What does this MR do?

This enables the feature flag api_keyset_pagination by default.

Related MRs/Issues are:

• Docs: !21035 (merged)
• Feature: !19623 (merged)
• Performance testing: #36159 (closed)

Closes #32186 (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.
• Tested in all supported browsers