Rails5 fix update_attribute usage not causing a save

What does this MR do?

Replaces update_attribute with update_attributes to make sure the import_status is saved. Rails 5 does a changed? check before calling save: https://github.com/rails/rails/blob/v5.0.7/activerecord/lib/active_record/persistence.rb#L264. This behaviour is reverted in the 5-0-stable branch, but is still unreleased: https://github.com/rails/rails/blob/5-0-stable/activerecord/lib/active_record/persistence.rb#L259.

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

rails5 upgrade

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• Conform by the merge request performance guides
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Closes #47960 (closed)