tests: refactor code to use a single test url generator

rhodecode/config/middleware.py

@@ -258,6 +258,8 @@ def error_handler(exception, request):
         '/errors/error_document.mako', {'c': c, 'h': helpers}, request=request,
         response=base_response)
 
+    response.headers["X-RC-Exception-Id"] = str(c.exception_id)
+
     statsd = request.registry.statsd
     if statsd and base_response.status_code > 499:
         exc_type = f"{exception.__class__.__module__}.{exception.__class__.__name__}"