Update path navigation to go to parent policies

What does this MR do and why?

Update path navigation to go to parent policies

• previously the path navigated the user to the parent project
• now it navigates the user to the parent's policies

Screenshots or screen recordings

N/A

How to set up and validate locally

1. Enable :group_level_security_policies feature flag
2. Upload a GitLab Ultimate license
3. Navigate to a group => Security & Compliance => Policies and assign a policy project with policies in it (using Update policy project selection for groups (!86981 - merged), but this MR is not dependent on it)
4. Navigate to a project in that group => Security & Compliance => Policies and assign a different policy project with policies in it
5. Verify the inheritance

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.

Related to #345321 (closed)

ee/app/assets/javascripts/threat_monitoring/components/utils.js

 import { getBaseURL, joinPaths } from '~/lib/utils/url_utility';
 
 export const getSourceUrl = (fullPath) => {
-  return joinPaths(getBaseURL(), fullPath);
+  return joinPaths(getBaseURL(), 'groups', fullPath, '-', 'security', 'policies');
 };
 
 export const isPolicyInherited = (source) => {