Add runtime warning for group and sub-group scan result policies

What does this MR do and why?

Describe in detail what your merge request does and why.

This MR adds a warning for group and sub-group level scan result policies about the time it may take to apply the changes.

The warning will not show up for group-level scan execution policies or project-level scan execution/result policies.

Related issue: #382808 (closed)

Screenshots or screen recordings

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

Policy Type	Project-level	Group-level
Scan Execution Policy
Scan Result Policy

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. Navigate to http://gdk.test:3443/flightjs/Flight/-/security/policies/new?type=scan_result_policy
3. Navigate to http://gdk.test:3443/flightjs/Flight/-/security/policies/new?type=scan_execution_policy
4. Navigate to http://gdk.test:3443/groups/flightjs/-/security/policies/new?type=scan_result_policy
5. Navigate to http://gdk.test:3443/groups/flightjs/-/security/policies/new?type=scan_execution_policy
6. Verify information on each page

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.