fix(cmd): resolve golangci-lint errors in test infrastructure

- Explicitly ignore fmt.Fprintf error in printOutput helper
- Remove unused setTestClient function
- Remove unused server field from MockClient struct

All linter checks now pass with zero issues.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: platinummonkey

cmd/root.go

@@ -130,16 +130,9 @@ func getClient() (*client.Client, error) {
 	return ddClient, nil
 }
 
-// setTestClient sets a mock client for testing and returns a cleanup function
-func setTestClient(mockClient *client.Client) func() {
-	original := ddClient
-	ddClient = mockClient
-	return func() { ddClient = original }
-}
-
 // printOutput writes formatted output (for testing)
 func printOutput(format string, a ...any) {
-	fmt.Fprintf(outputWriter, format, a...)
+	_, _ = fmt.Fprintf(outputWriter, format, a...)
 }
 
 // readConfirmation reads user confirmation from input

cmd/testutil/testutil.go

@@ -22,7 +22,6 @@ import (
 // MockClient provides a mock Datadog client for testing
 type MockClient struct {
 	*client.Client
-	server *httptest.Server
 }
 
 // NewMockClient creates a mock client that uses a test HTTP server