[SPARK-18027][YARN] .sparkStaging not clean on RM ApplicationNotFoundException

## What changes were proposed in this pull request?

Cleanup YARN staging dir on all `KILLED`/`FAILED` paths in `monitorApplication`

## How was this patch tested?

Existing tests

Author: Sean Owen <sowen@cloudera.com>

Closes #15598 from srowen/SPARK-18027.