Fix condition for checking if tests are defined

Native shell conditional is used as previously the condition
would give warnings on stderr in certain cases, e.g. when
role was removed script reported:
"find: ‘ansible/roles/<rolename>’: No such file or directory"

Change-Id: I63f50bda94e144a17307d927a6be70ae270f28bf
Signed-off-by: Bartek Grzybowski <b.grzybowski@partner.samsung.com>
Issue-ID: OOM-1853
diff --git a/offline-installer-review.sh b/offline-installer-review.sh
index 3e011ea..69f438d 100755
--- a/offline-installer-review.sh
+++ b/offline-installer-review.sh
@@ -36,7 +36,7 @@
   local MOLECULE_RC
   for role in ${roles[@]}
     do
-      if `find ${role} -name molecule.yml | grep -q '.*'`; then
+      if [ -f ${role}/molecule/default/molecule.yml ]; then
         ./ansible/test/bin/ci-molecule.sh ${role}
         MOLECULE_RC=$?
         if [ ${MOLECULE_RC} -ne "0" ]; then FAILED_ROLES+=(${role}); fi