Merge "Switch to Cortex-A72 cpu on AArch64"

tests/templates/nova-compute-overrides.j2

 [libvirt]
 {% if ansible_architecture == 'aarch64' %}
 cpu_mode=custom
-cpu_model=max
+# cpu_model=max fails to boot multiple images with QEMU 7.0 and -M virt (works with "-M virt-6.2")
+cpu_model=cortex-a72
 {% endif %}