Fixes bug with ama role assignments

[arjenhuitema]

Overview/Summary

Resolved an issue that prevented the policy remediation from working properly for VM Insights and Change Tracking policies. The root cause was the insufficient access granted to the Managed Identity that performs the remediation task. To solve the problem, we granted the Policy Assignments in the Landing Zone Management the permission to read the Platform Management Group.

This PR fixes/adds/changes/removes

1. Adds Role Assignments to VMInsights Policies at LZs MG granting rbacReader on Platform MG
2. Adds Role Assignments to ChangeTracking Policies at LZs MG granting rbacReader on Platform MG
3. Adds Role Assignments to Azure Update Manger Policies, granting rbacManagedIdentityOperator at the same scope as the assignment.

Breaking Changes

None

Testing Evidence

Deployment

Compliance Monitoring

Compliance Change Tracking

Compliance Azure Update Manager

Testing URLs

Azure Public

As part of this Pull Request I have

• Checked for duplicate Pull Requests
• Associated it with relevant issues, for tracking and closure.
• Ensured my code/branch is up-to-date with the latest changes in the main branch
• Performed testing and provided evidence.
• Ensured contribution guidance is followed.
• Updated relevant and associated documentation.
• Updated the "What's New?" wiki page (located: /docs/wiki/whats-new.md)