Fix request #7252 Fatal error on search when FTS plugin not installed

Change-Id: I86c19c5d2899c4bbaf0da307e6992a1a198daf58
Merge commit 'refs/changes/92/2792/1' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  Fix request #7252 Fatal error on search when FTS plugin not installed

Change-Id: Ia3ab250d065c8617718acc85fc4b12a32f38a504
This is Tuleap 7.2.99.64

Change-Id: I213841f7c68bcd6a17aced8b90d3552c120d4402