Refactor `backup/IoTDBDataBackTool.java` to resolve SonarQube issues

## Description

This task focuses on resolving multiple SonarCloud issues identified in `backup/IoTDBDataBackTool.java`.The file currently contains several maintainability and code quality violations, including:

- Update this logger to use "IoTDBDataBackTool.class".
- Rename this field "IS_OBJECT_STORAGE" to match the regular expression '^[a-z][a-zA-Z0-9]*$'.
- Use "isEmpty()" to check whether a "String" is empty or not.

## File
`iotdb-client/.../org/apache/iotdb/tool/backup/IoTDBDataBackTool.java`

## How to fix

```tsx
1.
LoggerFactory.getLogger(AbstractDataTool.class);
to
LoggerFactory.getLogger(IoTDBDataBackTool.class);

2.

static boolean IS_OBJECT_STORAGE = false;
to
static boolean isObjectStorage = false;

3.
targetWalDirParam.length() > 0;
to
targetWalDirParam.isEmpty();
```

## Sonar Issue

https://sonarcloud.io/project/issues?open=AY8JzfmBywzNF5Ghx44F&id=apache_iotdb

`Note: The goal is to improve readability, maintainability, and compliance with SonarCloud quality standards without changing existing functionality.`

Commencez par iotdb-client/.../org/apache/iotdb/tool/backup/IoTDBDataBackTool.java et examinez les problèmes SonarCloud listés dans l’issue. Mettez à jour de manière cohérente dans tout le fichier la classe logger, le nommage des champs et la vérification de chaîne vide, puis vérifiez que l’outil de backup se compile toujours et se comporte sans modifications fonctionnelles.

Rédigé par le modèle d'indexation à partir du texte de l'issue.