Fix get_reference_table: propagate limit to query args (#248)

* Fix get_reference_table: propagate limit to query args

The signature accepted and documented a `limit` parameter, but the
function never forwarded it into `query_args`, so every call fetched
at the schema/server default regardless of what the user requested.

Forward `limit` into a copy of the user-supplied `query` dict (so the
caller's dict is not mutated) when it is not None.

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

* Cover the limit + query branch with no-mutation assertion

Per copilot review on PR #248.

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

* Drop trivial regression tests for limit propagation

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

---------

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

Author: thodson-usgs

dataretrieval/waterdata/api.py

@@ -1542,7 +1542,9 @@ def get_reference_table(
     else:
         output_id = f"{collection.replace('-', '_')}"
 
-    query_args = query or {}
+    query_args = dict(query) if query else {}
+    if limit is not None:
+        query_args["limit"] = limit
     return get_ogc_data(args=query_args, output_id=output_id, service=collection)