Additionally fixes the bugs uncovered in:
- `MDEV-28332: Alter on temporary table causes ER_TABLE_EXISTS_ERROR note`
Since there is no `warning` issued by shadowing of base table, this MDEV
is irrelevant. Keeping for review purposes and for future development
in case shadowing is going to be implemented
- `MDEV-28334: SHOW TABLE STATUS shows all temporary tables ignoring database and conditions`
- `MDEV-28453: SHOW commands are inconsistent for temporary tables`
Reviewed by: <monty@mariadb.org>,
<vicentiu@mariadb.org>