[#64101] First section has "Move to top" and "Move up" actions

[mrmir]

Ticket

https://community.openproject.org/work_packages/64101

What are you trying to accomplish?

The backlog section being created as part of the create service for meetings breaks previous assumptions about the section at the first position. This PR fixes that by checking for the first section after the backlog when referring to the first section of a meeting.

Merge checklist

• [ ] Added/updated tests
• [ ] Added/updated documentation in Lookbook (patterns, previews, etc)
• [ ] Tested major browsers (Chrome, Firefox, Edge, ...)