Adapt test output dir to run tests in Docker

Plus generate a proper XML testsuite for PHPUnit so all tests are reported
once

Change-Id: I3da5c64e6a7acc6e1e8949f287025077e4008338
Merge commit 'refs/changes/18/2818/2' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  Adapt test output dir to run tests in Docker

Change-Id: I491bf5d584888d786d5ac9e9f5904fb9d9eecdc8
This is Tuleap 7.3.99.22

Change-Id: I7adef89f712fb8ee801ec9a9f463a34eb21e0318