Tighten _arrange_cols comments

Drop the regression-narrative phrasing for the local-copy comment and
trim the multi-line "id is technically a valid column..." block to a
two-line WHY explaining the rename intent.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: thodson-usgs

dataretrieval/waterdata/utils.py

@@ -687,14 +687,12 @@ def _arrange_cols(
     # If properties are provided, filter to only those columns
     # plus geometry if skip_geometry is False
     if properties and not all(pd.isna(properties)):
-        # Work on a local copy so we don't mutate the caller's list across calls.
+        # Don't alias the caller's list — we mutate below.
         local_properties = list(properties)
-        # Make sure geometry stays in the dataframe if skip_geometry is False
         if "geometry" in df.columns and "geometry" not in local_properties:
             local_properties.append("geometry")
-        # id is technically a valid column from the service, but these
-        # functions make the name more specific. So, if someone requests
-        # 'id', give them the output_id column
+        # 'id' is a valid service column, but expose it under the
+        # service-specific output_id name instead.
         if "id" in local_properties:
             local_properties[local_properties.index("id")] = output_id
         df = df.loc[:, [col for col in local_properties if col in df.columns]]