Default list_user_preferences.collapsed column to false on database

Default list_user_preferences.collapsed to FALSE on database to be consistent with boards_epic_list_user_preferences.collapsed.

Both columns share some code on services like like Boards::Lists::BaseUpdateService and other parts of the application and this difference can cause inconsistent behavior.

No data migration to update old records is required. We do not have list_user_preferences.collapsed as null on the database yet.

gitlabhq_production=> SELECT COUNT(*) FROM list_user_preferences WHERE collapsed IS NULL \g
 count 
-------
     0
(1 row)

For more information check: !58811 (diffs, comment 549930027)