[Bug][api] Data type conversion exception returned by LoggerService

LoggerService.queryLog() return paradigm type, ProcessInstanceService.addDependResultForTaskList() conversion error:
```java
String log = (String) logResult.getData();
```

Revised as:
```java
Result<String> logResult = loggerService.queryLog(taskInstance.getId(), 0, 4098);
String log = logResult.getData();
```

Avoid `ClassCastException`.