MDL-47808 mod_forum: Correct maxeditingtime for unit tests
MDL-47808 mod_forum: Correct maxeditingtime for unit tests

The maxeditingtime needs to be a negative value for unit tests to ensure
that the messages are actually sent out.

Whilst fixing this I also discovered that the create_discussion part of the
generator also creates the first post.

dilawar/moodle