Fix FetchPolicyApproversService for ComplianceFramework

What does this MR do and why?

This change fixes a bug in Security::SecurityOrchestrationPolicies::FetchPolicyApproversService when the container is ComplianceManagement::Framework.

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Before	After

How to set up and validate locally

• Create a compliance framework for a root group in Settings-> General -> Compliance Frameworks
• Create a security policy with compliance framework in the scope for the group
• Disable security_policy_global_group_approvers_enabled settings in rails-console:

Gitlab::CurrentSettings.current_application_settings.update(security_policy_global_group_approvers_enabled: false)

• Go to graphql-explorer and try the graphql query:

query {
  namespace(fullPath:<path of the group>) {
    complianceFrameworks {
      nodes {
        name
        scanResultPolicies {
          nodes {
            name
            allGroupApprovers {
              fullPath
            }
          }
        }
      } 
    }
  }
}