azurerm_cognitive_deployment - mark rai_policy_name as Computed (#32131)

[ENHANCEMENT] * `azurerm_cognitive_deployment` - the `rai_policy_name` property is now Optional + Computed as Azure returns a value when not set in the creation request

Author: ZiChuanBuXiu

internal/services/cognitive/cognitive_deployment_resource.go

@@ -166,8 +166,10 @@ func (r CognitiveDeploymentResource) Arguments() map[string]*pluginsdk.Schema {
 		},
 
 		"rai_policy_name": {
-			Type:         pluginsdk.TypeString,
-			Optional:     true,
+			Type:     pluginsdk.TypeString,
+			Optional: true,
+			// NOTE: O+C `raiPolicyName` has default value when `rai_policy_name` is not set. So, `O+C` is required otherwise it will incur difference.
+			Computed:     true,
 			ValidateFunc: validation.StringIsNotEmpty,
 		},