fix: update --appgw-subnet-cidr to be shorter than /24

Author: robogatikov

src/azure-cli/azure/cli/command_modules/acs/tests/latest/test_aks_commands.py

@@ -3566,13 +3566,14 @@ def test_aks_create_with_ingress_appgw_addon(self, resource_group, resource_grou
         })
 
         create_cmd = 'aks create --resource-group={resource_group} --name={name} --enable-managed-identity ' \
-                     '-a ingress-appgw --appgw-subnet-cidr 10.232.0.0/16 ' \
+                     '--aks-custom-headers AKSHTTPCustomFeatures=Microsoft.ContainerService/AppGatewayWithOverlayPreview ' \
+                     '-a ingress-appgw --appgw-subnet-cidr 10.232.0.0/26 ' \
                      '--ssh-key-value={ssh_key_value} -o json'
         self.cmd(create_cmd, checks=[
             self.check('provisioningState', 'Succeeded'),
             self.check('addonProfiles.ingressApplicationGateway.enabled', True),
             self.check(
-                'addonProfiles.ingressApplicationGateway.config.subnetCIDR', "10.232.0.0/16")
+                'addonProfiles.ingressApplicationGateway.config.subnetCIDR', "10.232.0.0/26")
         ])
 
     # live only due to role assignment is not mocked