oidc-proxy token request param fix (#15115)

Author: StekPerepolnen

ydb/mvp/oidc_proxy/oidc_session_create_nebius.cpp

@@ -19,7 +19,7 @@ void THandlerSessionCreateNebius::RequestSessionToken(const TString& code) {
 
     TCgiParameters params;
     params.emplace("code", code);
-    params.emplace("client_id", code);
+    params.emplace("client_id", Settings.ClientId);
     params.emplace("client_assertion_type", "urn:ietf:params:oauth:client-assertion-type:access_token_bearer");
     params.emplace("grant_type", "authorization_code");
     params.emplace("redirect_uri", TStringBuilder() << (Request->Endpoint->Secure ? "https://" : "http://")