Resolve "Don't raise an exception when the batch_size is 1"

What does this MR do and why?

When we retry a batched background migration via the admin panel, the system will split and retry all jobs. If one of these jobs has the batch_size the system will raise an exception and the customer will see the 500 Error screen.

To mitigate this, we reset the job attempts when the batch_size is one.

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Related to #367334 (closed)