fix: account for initial hash table allocation in ArrowBytesMap/ArrowBytesViewMap

ArrowBytesMap and ArrowBytesViewMap initialize their hash table with
with_capacity(INITIAL_MAP_CAPACITY) but set map_size to 0. The
insert_accounted method only tracks incremental growth beyond the
current capacity, so the initial allocation is never counted in
size() — understating memory usage.

Initialize map_size with map.allocation_size() to capture the
pre-allocated memory.

Author: yashrb24

datafusion/physical-expr-common/src/binary_map.rs

@@ -244,10 +244,12 @@ where
     V: Debug + PartialEq + Eq + Clone + Copy + Default,
 {
     pub fn new(output_type: OutputType) -> Self {
+        let map = hashbrown::hash_table::HashTable::with_capacity(INITIAL_MAP_CAPACITY);
+        let map_size = map.allocation_size();
         Self {
             output_type,
-            map: hashbrown::hash_table::HashTable::with_capacity(INITIAL_MAP_CAPACITY),
-            map_size: 0,
+            map,
+            map_size,
             buffer: BufferBuilder::new(INITIAL_BUFFER_CAPACITY),
             offsets: vec![O::default()], // first offset is always 0
             random_state: RandomState::default(),

datafusion/physical-expr-common/src/binary_view_map.rs

@@ -155,10 +155,12 @@ where
     V: Debug + PartialEq + Eq + Clone + Copy + Default,
 {
     pub fn new(output_type: OutputType) -> Self {
+        let map = hashbrown::hash_table::HashTable::with_capacity(INITIAL_MAP_CAPACITY);
+        let map_size = map.allocation_size();
         Self {
             output_type,
-            map: hashbrown::hash_table::HashTable::with_capacity(INITIAL_MAP_CAPACITY),
-            map_size: 0,
+            map,
+            map_size,
             views: Vec::new(),
             in_progress: Vec::new(),
             completed: Vec::new(),