Decrease page size for queries

Decrease query driver's default page size.  Queries were consuming excessive memory on Butler server, and lowering this value  does not seem to make queries any slower.  This reduces memory consumption for a dataset query with dimension records from ~120MB to ~30MB per in-flight query.

python/lsst/daf/butler/direct_query_driver/_driver.py

@@ -134,7 +134,10 @@ def __init__(
         dimension_record_cache: DimensionRecordCache,
         default_collections: Iterable[str],
         default_data_id: DataCoordinate,
-        raw_page_size: int = 10000,
+        # Increasing raw_page_size increases memory usage for queries on
+        # Butler server, so if you increase this you may need to increase the
+        # memory allocation for the server in Phalanx as well.
+        raw_page_size: int = 2000,
         constant_rows_limit: int = 1000,
         postprocessing_filter_factor: int = 10,
     ):