## What changes were proposed in this pull request?

Reload the `spark.yarn.credentials.file` property when restarting a streaming application from checkpoint.

## How was this patch tested?

Manual tested with 1.6.3 and 2.1.1.
I didn't test this with master because of some compile problems, but I think it will be the same result.

## Notice

This should be merged into maintenance branches too.

jira: [SPARK-21008](https://issues.apache.org/jira/browse/SPARK-21008)

Author: saturday_s <shi.indetail@gmail.com>

Closes #18230 from saturday-shi/SPARK-21008.