updating image used in a3ultra vm blueprint - older image is deprecated.

Author: arpit974

examples/machine-learning/a3-ultragpu-8g/a3ultra-vm.yaml

@@ -25,7 +25,7 @@ vars:
   a3u_provisioning_model: RESERVATION_BOUND
   instance_image:
     project: ubuntu-os-accelerator-images
-    family: ubuntu-accelerator-2204-amd64-with-nvidia-550
+    family: ubuntu-accelerator-2204-amd64-with-nvidia-570
   net0_range: 192.168.0.0/19
   net1_range: 192.168.64.0/18
   filestore_ip_range: 192.168.32.0/29