Decouple experiment toggle check and ff

What does this MR do and why?

Decouple experiment toggle check and ff

• decouple ci experiment from pipeline execution policy feature flag
• more information at &13266 (comment 1940288055)

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Page	Screenshot
Policy selector
Scan execution
Type filter

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Upload a GitLab Ultimate license
2. Enable the feature flag using echo "Feature.enable(:pipeline_execution_policy_type)" | rails c
3. Navigate to a group => Settings => General => Permissions
4. Ensure Security policy pipeline execution action is disabled
5. Navigate to a project in the group => Secure => Policies
6. Verify the type filter includes pipeline execution policy
7. Select New policy
8. Verify Pipeline Execution Policy is available to select

Related to #467067 (closed)