## What changes were proposed in this pull request?

In https://github.com/apache/spark/pull/14065

, we introduced a configurable credential manager for Spark running on YARN. Also two configs `spark.yarn.credentials.renewalTime` and `spark.yarn.credentials.updateTime` were added, one is for the credential renewer and the other updater. But now we just query `spark.yarn.credentials.renewalTime` by mistake during CREDENTIALS UPDATING, where should be actually `spark.yarn.credentials.updateTime` .

This PR fixes this mistake.

## How was this patch tested?

existing test

cc jerryshao vanzin

Author: Kent Yao <yaooqinn@hotmail.com>

Closes #16955 from yaooqinn/cred_update.

(cherry picked from commit 7363dde6)
Signed-off-by: Marcelo Vanzin <vanzin@cloudera.com>