[JENKINS-15634] Ignore aborted builds in age calculation for failing tests

When test fails in one build, then the second build is aborted - in the third one the age of a testcase failure will be 1 instead of 3 (example test could not be executed). In big projects with thousands of tests it is hard to determine the reason of failure in such situations as above. All the test results history is corrupted.

Maybe It is a good idea to ignore aborted builds in age calculation (when determinig failure starting point).