cleandata.sql for both PostgreSQL and MySQL requires some cleanup.

1. ezpackage table data is obsolete (refers to eZ Publish).

2. ezsite_data refer to eZ Publish and old release of eZ Platform 1.4.

3. During installation both for PostgreSQL and MySQL data import executes ~300 queries.
We can optimize cleandata.sql of ezpublish-kernel to import all data for each table in a single query by utilizing multi row inserts. This would slightly improve performance, but moreover would make those files more readable and maintenance friendly.