Make scan_plan_helper private (#3541) (#3553)

scan_plan_helper is an internal helper for local scan planning, not a
public extension point. Rename it to _scan_plan_helper to reflect its
intended visibility and update its only caller in inspect.py.

The method was introduced recently in d99936a and has not been part of
any released public API, so no deprecation shim is required.
Fixes: #3541

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# Rationale for this change

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Author: tanmayrauth

pyiceberg/table/__init__.py

@@ -2224,7 +2224,7 @@ def _manifest_planner(self) -> ManifestGroupPlanner:
     def partition_filters(self) -> KeyDefaultDict[int, BooleanExpression]:
         return self._manifest_planner.partition_filters
 
-    def scan_plan_helper(self) -> Iterator[list[ManifestEntry]]:
+    def _scan_plan_helper(self) -> Iterator[list[ManifestEntry]]:
         """Filter and return manifest entries based on partition and metrics evaluators.
 
         Returns:

pyiceberg/table/inspect.py

@@ -311,7 +311,7 @@ def partitions(
 
         partitions_map: dict[tuple[str, Any], Any] = {}
 
-        for entry in itertools.chain.from_iterable(scan.scan_plan_helper()):
+        for entry in itertools.chain.from_iterable(scan._scan_plan_helper()):
             partition = entry.data_file.partition
             partition_record_dict = {
                 field.name: partition[pos] for pos, field in enumerate(self.tbl.metadata.specs()[entry.data_file.spec_id].fields)