docs: update deprecated Azure AD terminology to Microsoft Entra ID

## Summary

Replace deprecated "Azure AD" terminology with the current 
"Microsoft Entra" branding per Microsoft's official rename 
(July 2023).

## Changes

| Location | Before | After |
|---|---|---|
| `billing/concepts/azure-subscriptions.md` | an **Azure AD** global administrator | a **Microsoft Entra** Global Administrator |

## Why

- Microsoft officially renamed Azure Active Directory to 
  **Microsoft Entra ID** in July 2023.
- The role name **Global Administrator** remains unchanged; 
  only the product prefix requires updating.

## References

- [Microsoft Entra rename announcement](https://learn.microsoft.com/en-us/entra/fundamentals/new-name)
- [Microsoft Entra built-in roles – Global Administrator](https://learn.microsoft.com/en-us/entra/identity/role-based-access-control/permissions-reference#global-administrator)

Author: zer0big

content/billing/how-tos/set-up-payment/connect-azure-sub.md

@@ -30,7 +30,7 @@ You can pay for metered usage of {% data variables.product.github %} features th
 
 * You must know your Azure subscription ID. See [Get subscription and tenant IDs in the Azure portal](https://learn.microsoft.com/en-us/azure/azure-portal/get-subscription-tenant-id) in the Microsoft Docs.
 
-* You must be logged into Azure as a user who is able to provide tenant-wide admin consent or arrange to work with an Azure AD global administrator to configure an admin consent workflow. See [AUTOTITLE](/billing/concepts/azure-subscriptions).
+* You must be logged into Azure as a user who is able to provide tenant-wide admin consent or arrange to work with a Microsoft Entra Global Administrator to configure an admin consent workflow. See [AUTOTITLE](/billing/concepts/azure-subscriptions).
 
 ## Connecting your Azure subscription to an organization or enterprise account