Aggregate junit results at parent test level

[llxia]

Currently, we only aggregate child TAP at the parent test build level.

It would be nice if we could do the same for JUnit test results (i.e., openjdk tests).

• JUnit result at the child job level: https://openj9-jenkins.osuosl.org/job/Test_openjdk17_j9_sanity.openjdk_aarch64_linux_OMR_testList_1/252/testReport/

• https://github.com/adoptium/aqa-tests/blob/master/buildenv/jenkins/JenkinsfileBase#L985

That is, we can see the aggregated child job JUnit results at the parent build level.