fix: use PUT method for ADC server /validate endpoint

The ADC server registers PUT /validate (not POST), matching the
same HTTP method used for PUT /sync.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: AlinsRan

internal/adc/client/executor.go

@@ -252,7 +252,7 @@ func (e *HTTPADCExecutor) runHTTPValidateForSingleServer(ctx context.Context, se
 		return fmt.Errorf("failed to load resources from file %s: %w", filePath, err)
 	}
 
-	req, err := e.buildHTTPRequest(ctx, serverAddr, config, labels, types, resources, http.MethodPost, "/validate")
+	req, err := e.buildHTTPRequest(ctx, serverAddr, config, labels, types, resources, http.MethodPut, "/validate")
 	if err != nil {
 		return fmt.Errorf("failed to build validate request: %w", err)
 	}

internal/webhook/v1/adc_validation_test.go

@@ -86,6 +86,6 @@ func managedIngressClassWithGatewayProxyMode(endpoint, mode string) []runtime.Ob
 
 func requireValidateRequest(t *testing.T, r *http.Request) {
 	t.Helper()
-	require.Equal(t, http.MethodPost, r.Method)
+	require.Equal(t, http.MethodPut, r.Method)
 	require.Equal(t, "/validate", r.URL.Path)
 }