Fix request #6987 deleted trackers are shown in the REST api /trackers/:id

Change-Id: Ie99f4ab5539c4276c719ac33a1ff544f06f4db71
Merge commit 'refs/changes/33/2633/3' of ssh://gerrit.tuleap.net:29418/tuleap into tuleap-stable-master

* ssh://gerrit.tuleap.net:29418/tuleap:
  Fix request #6987 deleted trackers are shown in the REST api /trackers/:id

Change-Id: Ib3370d130db24c92cb88f6d9ec9f46ecd8516b49
Tuleap 7.1.99.31

Change-Id: I7ad4d2d741fb454de1cbf02f19e7a71ab618349f