Sync description to work_item_description record

What does this MR do and why?

Sync description to work_item_description record

This upserts the description and the other attributes to the work_item_description record.

It's part of an effort to split the issues table and move out the description: &18643

The reason why I choose to sync this in application logic, instead of using a trigger:

• At some point, the work_item_description record will be the source of truth for reading
• Then we want to stop writing to the issues table
• At this point, we need to replace all changes to issues.description to work_item_description in the application logic
• However, we can at this point not be 100% sure that we catch all places in the application logic, because the trigger takes over that syncing work

So I rather put syncing into the application logic now, instead of later, to catch potential syncing bugs early.

References

#556921

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Create or update a work item
2. Go into the rails console and check if it got the right content on the work_item_description record:

work_item = WorkItem.find(WORK_ITEM_ID)
work_item.work_item_description

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