[SPARK-12155][WIP] Fix bug in eviction of storage memory by execution w/ multiple active tasks

[JoshRosen]

Whoops, accidentally clicked the open PR button. This is just a regression test for now.

[SparkQA]

Test build #47444 has finished for PR 10230 at commit 8e7f099.

• This patch fails to build.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #47454 has finished for PR 10230 at commit f1b1aac.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * logInfo(s\"HBase class not found $e\")\n * logDebug(\"HBase class not found\", e)\n

[JoshRosen]

See Andrew's PR for the final fix that we came up with: #10240.