Add ignore changes tempaltes to monitoring terraform (#4926)

It adds the flag to ignore changes on monitoring terraform. 

Its needed to reduce the noise on the terraform plan.

Terraform plan without the noise after changes.
<img width="1330" height="814" alt="image"
src="https://github.com/user-attachments/assets/d7b7d75a-a2d3-4e54-b376-4b1acef525b5"
/>

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Signed-off-by: Javan Lacerda <javanlacerda@google.com>

Author: javanlacerda

infra/terraform/monitoring.tf

@@ -20,6 +20,11 @@ provider "google" {
 
 resource "google_monitoring_dashboard" "clusterfuzz_sli_dashboard" {
   provider = google.monitoring
+  lifecycle {
+    ignore_changes = [
+      dashboard_json,
+    ]
+  }
   dashboard_json = <<JSON
 {
   "displayName": "Clusterfuzz Relability Metrics",