Bug: Agent Inventory usage request returns 403 while PPAC succeeds

Description

The licensing HTTP request used by Agent Inventory | Usage Data Load (GrandChild) returns 403 Forbidden, preventing Copilot Studio credit usage from being retrieved. Usage remains available in Power Platform admin center for the same admin account.

The affected request is shipped in CopilotStudioAccelerator-August2026.1:

GET https://licensing.powerplatform.microsoft.com/v2.0/tenants/{tenantId}/entitlements/MCSMessages/resources

The connector reports:

{
  "code": 403,
  "message": "The response is not in a JSON format.",
  "innerError": "Cannot read server response."
}

Expected behavior

Agent Inventory can retrieve Copilot Studio credit usage through its documented licensing connection.

Requested help

Have the licensing endpoint or authorization requirements changed? Please advise on a fix for the Agent Inventory usage flow.

This resembles the symptoms previously reported in #628.