Carousel creation from items can create duplicate entries

[Jane Sandberg]

This is a follow-up for bug 1906859 that we discovered in the collaborative code review.

Steps to recreate:

1. Create an item bucket
2. Add 5 items that are attached to the same bib, and 1 item that is attached to a different bib.
3. Under the bucket menu, press Create Carousel from Bucket
4. Look at the bib record bucket that was newly created
5. Notice that only 2 records show, but it says "6 records". This is because the same bib record is in there five times!
6. Notice that the carousel displays the same bib 5 times, then the other bib only once.

[Terran McCanna (tmccanna)]

Noting that this is related to the fact that item and record buckets can contain duplicate rows - see related bugs:

https://bugs.launchpad.net/evergreen/+bug/1814183

https://bugs.launchpad.net/evergreen/+bug/1873888

https://bugs.launchpad.net/evergreen/+bug/1771568

https://bugs.launchpad.net/evergreen/+bug/1485695

Ideally, a more complete solution would be for the database to prevent duplicate rows from being added to any bucket.

[Jane Sandberg (sandbergja)]

Here is a narrow fix, just for the case of creating carousels from items: user/sandbergja/lp2059034-no-duplicates-in-item-carousels

Here is the link: https://git.evergreen-ils.org/?p=working/Evergreen.git;a=shortlog;h=refs/heads/user/sandbergja/lp2059034-no-duplicates-in-item-carousels