Add duo_remote_flows_enabled cascading setting

What does this MR do and why?

This code change adds a new feature called "Duo Flow" settings to GitLab's AI configuration interface. The main changes include:

New Feature Addition: A new setting called "Allow flow execution" has been added to the GitLab Duo AI settings pages, allowing administrators to control whether AI agents can execute automated workflows (called "flows").

User Interface Updates: The changes create a new settings component with a checkbox that lets users enable or disable flow execution, complete with help text explaining what flows are and links to documentation.

Data Flow Integration: The new setting is connected throughout the application - from the user interface forms down to the backend data storage, ensuring the setting can be saved and retrieved properly.

Administrative Control: The feature is integrated into both group-level and instance-level AI settings, giving administrators granular control over this functionality.

Visual Improvements: Some minor styling adjustments were made to improve the layout of the settings interface.

The overall purpose is to give GitLab administrators more control over AI-powered automation features, specifically the ability to allow or prevent AI agents from executing predefined workflows within their GitLab instance or groups.

References

Screenshots or screen recordings

Disabling instance setting

Screen Recording 2025-09-05 at 13.31.05.mov

Disabling Group setting

Screen Recording 2025-09-05 at 13.34.22.mov

Disabling project setting

Screen Recording 2025-09-05 at 13.37.03.mov

How to set up and validate locally

1. Make sure you have AI features enabled https://docs.gitlab.com/development/ai_features/
2. Turn on two feature flags: duo_workflow and duo_workflow_in_ci
3. Make sure your project has experimental ai features turned on
4. Pull this Branch down and checkout to it
5. rebase / cherry-pick commits from !202745 (merged)
6. Navigate to an issue
7. Notice the generate MR from issue button
8. Go to the admin settings => GitLab Duo
9. Configure
10. Turn off the flow feature
11. Navigate to any sub group with ai features
12. Go to the general settings => gitlab duo
13. Notice the flow setting is locked
14. Navigate to an issue of this group
15. Notice the generate MR from issue button is gone
16. Turn back on the instance setting
17. Go to an issue
18. Notice the button is shown
19. Turn off the flow setting in a group
20. in a sub project, check an issue
21. Notice the button is not shown
22. Turn on the group setting
23. Go to an issue
24. Notice the button is shown
25. Go to a project
26. Turn off the flow settings
27. go to an issue
28. notice the button is not shown
29. Turn on the project
30. Go to an issue
31. Notice the button is shown

MR acceptance checklist

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