refactor: remove unused max_search_results config parameter

The max_search_results configuration parameter was only used in one
location and added unnecessary complexity. Search operations now use
a consistent default page size of 20, which aligns with the pagination
implementation and provides better user experience.

Changes:
- Remove max_search_results from CordraConfig
- Update search_objects to use default page size of 20
- Simplify tests by removing config mocking
- Maintain backward compatibility through limit parameter

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

tests/test_client.py

@@ -413,6 +413,5 @@ class TestCordraConfig:
         assert config.base_url == "https://localhost:8443"
         assert config.username is None
         assert config.password is None
-        assert config.max_search_results == 1000
         assert config.verify_ssl is True
         assert config.timeout == 30