Resolve policies read access when user is not member of policy project

What does this MR do and why?

1. Fixes bug with read policies permission which was checking on the policy management project instead of the source project.
2. The frontend changes for this as proposed will be covered in separate MR.

Related to #400202 (closed)

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Create a policy management project for a source project.
2. On the source project add a user say test with developer access.
3. Login separately as the test user and visit the source project. Source project -> Security and Compliance -> Policies
4. Test user with developer access should be able to view the policies configured.

MR acceptance checklist

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

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