Description

Previously, if create/drop table under system databases such like:

create table information_schema.ins_test (ts timestamp, c1 int);
drop table information_schema.ins_users;

It reported "Vnode is closed or removed" which was hard to understand
for users. The patch changes it to more meaningful message such like
"Cannot create/drop table of system database..." for better user experience.

Checklist

Please check the items in the checklist if applicable.

• Is the user manual updated?
• Are the test cases passed and automated?
• Is there no significant decrease in test coverage?