Update depraction date for IAP OAuth APIs. (#15260)

Author: bryan0515

mmv1/products/iap/Brand.yaml

@@ -14,7 +14,11 @@
 ---
 name: 'Brand'
 deprecation_message: >-
-  after July 2025, the `google_iap_brand` Terraform resource will no longer function as intended due to the deprecation of the IAP OAuth Admin API
+  This resource is deprecated on Jan 22, 2025.
+  After Jan 19, 2026 the `google_iap_brand` Terraform resource will no longer function as intended
+  due to the deprecation of the IAP OAuth Admin APIs. New projects will not be able to use these APIs.
+  March 19, 2026 The IAP OAuth Admin APIs will be permanently shut down.
+  Access to this feature will no longer be available.
 description: |
   OAuth brand data. Only "Organization Internal" brands can be created
   programmatically via API. To convert it into an external brands

mmv1/products/iap/Client.yaml

@@ -15,7 +15,11 @@
 name: 'Client'
 api_resource_type_kind: IdentityAwareProxyClient
 deprecation_message: >-
-  After July 2025, the `google_iap_client` Terraform resource will no longer function as intended due to the deprecation of the IAP OAuth Admin API
+  This resource is deprecated on Jan 22, 2025.
+  After Jan 19, 2026 the `google_iap_client` Terraform resource will no longer function as intended
+  due to the deprecation of the IAP OAuth Admin APIs. New projects will not be able to use these APIs.
+  March 19, 2026 The IAP OAuth Admin APIs will be permanently shut down.
+  Access to this feature will no longer be available.
 description: |
   Contains the data that describes an Identity Aware Proxy owned client.