add boskos config to arm64

Author: medyagh

hack/prow/boskos-cfg-arm64.json

@@ -0,0 +1,9 @@
+{
+    "GCPZone": "us-central1-b",
+    "InstanceImage": "ubuntu-os-cloud/ubuntu-2404-lts-arm64",
+    "InstanceType": "t2a-standard-8",
+    "DiskGiB": 300,
+    "BoskosAcquireTimeoutSeconds": 180,
+    "BoskosHeartbeatIntervalSeconds": 10,
+    "BoskosLocation": "http://boskos.test-pods.svc.cluster.local"
+}