Fix scheduling epic migration

What does this MR do?

• Original MR: !32926 (closed)

This MR fixes ArgumentError: wrong number of arguments (given 3, expected 1..2) when running background migration MoveEpicIssuesAfterEpics.

as discussed in the MR we don't want to re-run the migration, we just want to fix the migration for older installations.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.