chore: improve neighbor stat log (#4561)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Documentation**
- Improved logging statements in the `NeighborStat` class for better
clarity and detail
- Enhanced log messages to include more descriptive information about
neighbor distances and sizes

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Signed-off-by: Jinzhe Zeng <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

deepmd/utils/neighbor_stat.py

@@ -81,8 +81,12 @@ def get_stat(self, data: DeepmdDataSystem) -> tuple[float, np.ndarray]:
 
         # do sqrt in the final
         min_nbor_dist = math.sqrt(min_nbor_dist)
-        log.info("training data with min nbor dist: " + str(min_nbor_dist))
-        log.info("training data with max nbor size: " + str(max_nbor_size))
+        log.info(
+            f"Neighbor statistics: training data with minimal neighbor distance: {min_nbor_dist:f}"
+        )
+        log.info(
+            f"Neighbor statistics: training data with maximum neighbor size: {max_nbor_size!s} (cutoff radius: {self.rcut:f})"
+        )
         return min_nbor_dist, max_nbor_size
 
     @abstractmethod