Remove the group name prefix from testng report

[niuxuetao]

The group name as test class package prefix was introduced to let Testng sort tests by paxml group for the order of execution. However this couples the group name into test case name, which would break some testng statistics if the group name is changed (e.g. Jenkins).

To manipulate the test execution order, an alternative is to implement testng's IMethodInterceptor to do the sorting.

The <parameter name="paxmlTestNamePrefixWithPid" value="true" /> workaround is no longer needed.

[niuxuetao]

done in r1.8