box: remove compatibility mode for privileges

Before version 1.7.7 there were no CREATE or ALTER privileges.
READ+WRITE permitted object creation and altering.
In 1.10 CREATE and ALTER privileges were introduced together with a
compatibility mode in access_check_ddl() which assumed user had CREATE
and ALTER if it had READ and WRITE on a respective object.
Now its time for us to remove this compatibility mode.

Part of #3539