## What changes were proposed in this pull request?

In `PruneFileSourcePartitions`, we will replace the `LogicalRelation` with a pruned one. However, this replacement may change the output of the `LogicalRelation` if it doesn't have `expectedOutputAttributes`. This PR fixes it.

## How was this patch tested?

the new `PruneFileSourcePartitionsSuite`

Author: Wenchen Fan <wenchen@databricks.com>

Closes #15569 from cloud-fan/partition-bug.