Do not show all completed migrations in batch message

Problem/Motivation

While discussing 🐛 Placement of batch progress messages Active at 📌 Drupal Usability Meeting 2023-07-28 Fixed , we considered further improvements to the feedback when executing a migration through the admin UI.

We agreed that listing migrations that finished normally is not useful. It would be more helpful to show only those that have error or warning messages. When the process completes, the user is given a link to the logs, and that will show all the completed migrations,

After #2569785, the progress bar will show at the top, followed by the currently running migration and then up to 20 completed migrations, most recent first. Since the progress bar will no longer be below the list, it is less important to limit the list to 20 items.

Proposed resolution

Show the following elements, in this order:

• Progress bar
• Currently executing migration
• All completed migrations with errors or warnings, most recent first

Remaining tasks

User interface changes

Before

This screenshot is from 🐛 Placement of batch progress messages Active . After that issue, the progress bar will be at the top instead of the bottom.

API changes

None

Data model changes

None

Release notes snippet

N/A