[SUREFIRE-1978] logging testcases to separate logs

**[Wojciech](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=JIRAUSER283423)** opened **[SUREFIRE-1978](https://issues.apache.org/jira/browse/SUREFIRE-1978?redirect=false)** and commented

At this moment logs from testcases are in the file named after testsuite f.e:

```java
target/surefire-reports/org.apache.hadoop.hdfs.server..diskbalancer.command.TestDiskBalancerCommand-output.txt
```

It is no way to determine which log there is from which testcase. It would be useful to have separate log for separate testcase f.e:

```java
target/surefire-reports/org.apache.hadoop.hdfs.server..diskbalancer.command.TestDiskBalancerCommand_testCancelCommand-output.txt
```

---
No further details from [SUREFIRE-1978](https://issues.apache.org/jira/browse/SUREFIRE-1978?redirect=false)

Start by tracing how Surefire produces the logs under target/surefire-reports, using the TestDiskBalancerCommand-output.txt example as the current behavior. Determine where testcase names are available when logs are written, then verify that each testcase gets a distinct log such as TestDiskBalancerCommand_testCancelCommand-output.txt and that the existing suite-level naming remains understood.

Written by the indexing model from the issue text.