Fix govet+staticcheck issues (#20263)

This is better: https://github.com/golang/go/issues/60529

cmd/object-api-multipart_test.go

@@ -79,7 +79,7 @@ func testObjectNewMultipartUpload(obj ObjectLayer, instanceType string, t TestEr
 		case InvalidUploadID:
 			t.Fatalf("%s: New Multipart upload failed to create uuid file.", instanceType)
 		default:
-			t.Fatalf(err.Error())
+			t.Fatal(err.Error())
 		}
 	}
 }