cleanup: remove reduntant variable

scripts/mysql_install_db.sh

@@ -507,11 +507,9 @@ cat_sql()
 
   case "$auth_root_authentication_method" in
     normal)
-      echo "SET @skip_auth_root_nopasswd=NULL;"
       echo "SET @auth_root_socket=NULL;"
       ;;
     socket)
-      echo "SET @skip_auth_root_nopasswd=1;"
       echo "SET @auth_root_socket='$auth_root_socket_user';"
       ;;
   esac

scripts/mysql_system_tables_data.sql

@@ -42,7 +42,7 @@ IF @auth_root_socket is not null THEN
   IF not exists(select 1 from information_schema.plugins where plugin_name='unix_socket') THEN
      INSTALL SONAME 'auth_socket'; END IF; END IF;
 
-INSERT INTO global_priv SELECT * FROM tmp_user_nopasswd WHERE @had_user_table=0 AND @skip_auth_root_nopasswd IS NULL;
+INSERT INTO global_priv SELECT * FROM tmp_user_nopasswd WHERE @had_user_table=0 AND @auth_root_socket IS NULL;
 INSERT INTO global_priv SELECT * FROM tmp_user_socket WHERE @had_user_table=0 AND @auth_root_socket IS NOT NULL;
 DROP TABLE tmp_user_nopasswd, tmp_user_socket;