[SPARK-21721][SQL] Clear FileSystem deleteOnExit cache when paths are successfully removed

## What changes were proposed in this pull request?

We put staging path to delete into the deleteOnExit cache of `FileSystem` in case of the path can't be successfully removed. But when we successfully remove the path, we don't remove it from the cache. We should do it to avoid continuing grow the cache size.

## How was this patch tested?

Added a test.

Author: Liang-Chi Hsieh <viirya@gmail.com>

Closes #18934 from viirya/SPARK-21721.