Bug 1298646: No point in adding columns to the interaction_forum_post table
just to immediately drop them again.
Also, there were some lingering "accesstype IS NULL" checks in the elasticsearch
access queries, which should have been removed along with the "accesstype != objectionable"
that they were previously parenthetical with.
And, the artefact_access table doesn't need to accept "objectionable" as
an accesstype enum value anymore.
Signed-off-by: Yuliya Bozhko <email@example.com>