Move `tempfile` crate to dev dependencies in datafusion core crate

### Is your feature request related to a problem or challenge?

`tempfile` crate is currently included as a normal dependency in the `datafusion` crate. It would be possible to move the dependency to the `dev-dependencies` since the `tempfile` capabilities are only used by integration and unit tests.

Specifically, the following function:

```
/// Generate CSV partitions within the supplied directory
pub fn populate_csv_partitions(
tmp_dir: &TempDir,
partition_count: usize,
file_extension: &str,
) -> Result {
...
```
It is the only one that uses `tempfile` capabilities.

### Describe the solution you'd like

It would be possible to move the `tempfile` crate from `dependencies` to `dev-dependencies` by decorating the `populate_csv_partitions` with the `#[cfg(test)]` attribute and replicating the function where needed in the integration tests (i.e.: `datafusion/core/tests/dataframe/mod.rs`)

### Describe alternatives you've considered

_No response_

### Additional context

I'm opening this as a feature request since it's not an actual bug.

Repérez les déclarations de dépendances du datafusion core crate et toutes les utilisations de populate_csv_partitions, puis examinez datafusion/core/tests/dataframe/mod.rs pour trouver le helper de test d’intégration. Confirmez que tempfile n’est nécessaire que pour les tests, déplacez-le dans l’ensemble des dépendances de test et assurez-vous que les tests unitaires et d’intégration compilent et réussissent toujours.

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