Set proper autoincrement values for PostgreSQL

### Issue
Install Joomla (current staging) on PostgreSQL without Sample Data.
Try to create a module. It will fail with an error message related to the assets id.

### Reason
During installation, we insert data together with a fixed ID into various tables. In PostgreSQL you need to adjust the sequence number (= autoincrement value) after you manually inserted an ID.
We did that for some tables but not for all. The #__assets one was missing for example.

### Solution
This PR adds the queries to set the next sequence value for those tables that have a serial ID and after we manually inserted IDs.
It also removes some unneeded `nextval` (which only increments the sequence number) and one `setval` (because there is no serial ID in that table).

#### Testing
Make sure you can create modules, categories and the like.