Add condition for fixed value search in perform_search_with_system

- Update `perform_search_with_system` to exclude execution when `fixed_value_search?` is true.
- Improve condition handling for token search parameters.

Author: projkov

lib/inferno_suite_generator/test_modules/search_test.rb

@@ -217,7 +217,7 @@ def perform_search(params, patient_id)
       end
 
       perform_reference_with_type_search(params, resources_returned.count) if test_reference_variants?
-      perform_search_with_system(params, patient_id) if token_search_params.present?
+      perform_search_with_system(params, patient_id) if token_search_params.present? && !fixed_value_search?
 
       resources_returned
     end