`spark.unsafe.exceptionOnMemoryLeak` is present in the config of surefire.

```
        <!-- Surefire runs all Java tests -->
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.18.1</version>
          <!-- Note config is repeated in scalatest config -->
...

<spark.unsafe.exceptionOnMemoryLeak>true</spark.unsafe.exceptionOnMemoryLeak>
            </systemProperties>
...
```

 but is absent in the config ScalaTest.

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #7308 from sarutak/add-setting-for-memory-leak and squashes the following commits:

95644e7 [Kousuke Saruta] Added a setting for memory leak