default `ProxyType` for prop override extension

agent/envoyextensions/builtin/property-override/property_override.go

@@ -261,6 +261,9 @@ func (p *propertyOverride) validate() error {
 		}
 	}
 
+	if p.ProxyType == "" {
+		p.ProxyType = api.ServiceKindConnectProxy
+	}
 	if err := validProxyTypes.CheckRequired(string(p.ProxyType), "ProxyType"); err != nil {
 		resultErr = multierror.Append(resultErr, err)
 	}

agent/envoyextensions/builtin/property-override/property_override_test.go

@@ -236,7 +236,7 @@ func TestConstructor(t *testing.T) {
 		// enforces expected behavior until we do. Multi-member slices should be unaffected
 		// by WeakDecode as it is a more-permissive version of the default behavior.
 		"single value Patches decoded as map construction succeeds": {
-			arguments: makeArguments(map[string]any{"Patches": makePatch(map[string]any{})}),
+			arguments: makeArguments(map[string]any{"Patches": makePatch(map[string]any{}), "ProxyType": nil}),
 			expected:  validTestCase(OpAdd, extensioncommon.TrafficDirectionOutbound, ResourceTypeRoute).expected,
 			ok:        true,
 		},