Rollback not performed in reverse order from UI

Problem/Motivation

The dashboard UI uses the wrong operation name for immediate rollback when testing whether the migration order should be reversed. This causes dependencies to be rolled back before their dependent migrations. I have also had cases where the dashboard failed to load after an incomplete deregistration left dependent migrations in place without their dependencies.

Proposed resolution

Use the right operation name for immediate rollback and reverse the migration order for the deregister operation.