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

Author: robogatikov

src/aks-preview/azext_aks_preview/tests/latest/test_aks_commands.py

@@ -783,7 +783,7 @@ def test_aks_create_with_ingress_appgw_addon(
 
         create_cmd = (
             "aks create --resource-group={resource_group} --name={name} --enable-managed-identity "
-            "-a ingress-appgw --appgw-subnet-cidr 10.232.0.0/16 "
+            "-a ingress-appgw --appgw-subnet-cidr 10.232.0.0/26 "
             "--ssh-key-value={ssh_key_value} -o json"
         )
         self.cmd(
@@ -793,7 +793,7 @@ def test_aks_create_with_ingress_appgw_addon(
                 self.check("addonProfiles.ingressApplicationGateway.enabled", True),
                 self.check(
                     "addonProfiles.ingressApplicationGateway.config.subnetCIDR",
-                    "10.232.0.0/16",
+                    "10.232.0.0/26",
                 ),
             ],
         )