[Improvement][Spark]: Neo4j2GraphAr change the type

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

The former data type is Long in neo4j. But after importer, it becomes string when there is a null.

Just like [this](https://github.com/GraphScope/gar-test/blob/main/neo4j/Person.vertex.yml#L11).

### Expected Behavior

Fix it.

### Minimal Reproducible Example

Maybe [this](https://github.com/GraphScope/gar-test/blob/main/neo4j/Person.vertex.yml#L11).

### Environment

- Operating system: ubuntu
- GraphAr version: latest

### Link to GraphAr Logs

_No response_

### Further Information

_No response_