fix: delete the deprecated field for model monitor (#5274)

* fix: delete the deprecated field for model monitor

PiperOrigin-RevId: 627075504

Source-Link: googleapis/googleapis@5fa62a9

Source-Link: googleapis/googleapis-gen@a557727
Copy-Tag: eyJwIjoicGFja2FnZXMvZ29vZ2xlLWNsb3VkLWFpcGxhdGZvcm0vLk93bEJvdC55YW1sIiwiaCI6ImE1NTc3MjdhN2NkYzM2YjA5ODJiN2ExNTA5OWFjMjA5N2UwMjY1YWUifQ==

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>
Co-authored-by: sofisl <[email protected]>

Author: gcf-owl-bot[bot]

packages/google-cloud-aiplatform/protos/google/cloud/aiplatform/v1beta1/model_monitor.proto

@@ -175,10 +175,4 @@ message ModelMonitoringSchema {
 
   // Target /ground truth names of the model.
   repeated FieldSchema ground_truth_fields = 3;
-
-  // The prediction instance type that the Model accepts when serving.
-  // Supported values are:
-  // * `object`: Each input is a JSON object format.
-  // * `array`: Each input is a JSON array format.
-  string instance_type = 4;
 }