Revert "Access-Control-Allow-Origin header for GET /control-vectors"

This reverts commit 80508e1.

Author: trollkotze

examples/server/server.cpp

@@ -3184,7 +3184,6 @@ int main(int argc, char ** argv) {
     };
 
     const auto handle_get_control_vectors = [&ctx_server](const httplib::Request & req, httplib::Response & res) {
-      res.set_header("Access-Control-Allow-Origin", req.get_header_value("Origin"));
       json vectors = json::array();
 
       for (const auto & vec : ctx_server.params.control_vectors) {