Fix Security navigation for users with custom role

What does this MR do and why?

It fixes the Project sidebar and shows Vulnerabilities menu item (under Secure) for users who have enabled reading vulnerabilities because of their custom role.

Screenshots or screen recordings

How to set up and validate locally

1. Enable feature flag Feature.enable(:custom_roles_vulnerability)
2. Creates a personal access token with the API scope.
3. Pick a group with at least one project (project), pick a user who is member of this project (gues access level) - user
4. Check if a user can access the vulnerability page of the project (eg. https://gdk.test:3443/flightjs/Flight/-/security/vulnerability_report), they should not be able to access it
5. Create a custom role using the API: https://docs.gitlab.com/ee/api/member_roles.html#add-a-member-role-to-a-group
   • curl --request POST --header "Content-Type: application/json" --header "Authorization: Bearer $YOUR_ACCESS_TOKEN" --data '{"base_access_level" : 10, "read_vulnerability" : true}' "https://gdk.test:3443/api/v4/groups/$YOUR_GROUP_ID/member_roles"
   • You can also test with base_access_level = 10 which should not work (minimal base access level is reporter)
6. Associates the member with the role using the Group and Project Members API endpoint
   • curl --request PUT --header "Content-Type: application/json" --header "Authorization: Bearer $YOUR_ACCESS_TOKEN" --data '{"member_role_id": '$MEMBER_ROLE_ID', "access_level": 10}' "https://example.gitlab.com/api/v4/projects/$ID/members/$GUEST_USER_ID"
7. Check the menu sidebar when logged in with that user

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 #410126 (closed)