include InterfaceError for mariadb disconnect check

include InterfaceError for mariadb disconnect check

Corrected the error classes inspected for the "is_disconnect" check for the
``mariadbconnector`` dialect, which was failing for disconnects that
occurred due to common MySQL/MariaDB error codes such as 2006; the DBAPI
appears to currently use the ``mariadb.InterfaceError`` exception class for
disconnect errors such as error code 2006, which has been added to the list
of classes checked.

For the current "real reconnect test", shutting down the mariadb
connection from the client side produces
ProgrammingError("Connection isn't valid anymore") which we also
continue to intercept.

Fixes: #7457
Change-Id: I0b37cd7a73359a23ad756ff2af0a9333c841221b