Bug#37009970 authentication_openid_connect_client plugin remembers

token-file variable between sessions

Problem: When using the authentication_openid_connect_client plugin by
MySQL shell, it was found out, that token-file path provided is
remembered between sessions and there is no proper way to clear it.

Fix: authentication_openid_connect_client_id_token_file can be set to
nullptr.

Change-Id: I08a5b74025f81d4400419e022df173f018903b98

Author: Samar Pratap Singh

libmysql/authentication_openid_connect_client/authentication_openid_connect_client_plugin.cc

@@ -235,7 +235,7 @@ static int authentication_openid_connect_client_option(const char *option,
   const char *value = static_cast<const char *>(val);
   if (strcmp(option, "id-token-file") == 0) {
     free_plugin_option(s_id_token_location);
-    if (value == nullptr) return 1;
+    if (value == nullptr) return 0;
     const std::ifstream file(value);
     if (file.good()) {
       s_id_token_location = my_strdup(PSI_NOT_INSTRUMENTED, value, MYF(MY_WME));