functional tests: correctly remove database after a test

A databses for tests are created with double quoted name and were dropped
without quoting its names. Unqoted identifires are made lowered case
and quoted preserve letters cases, so when a test database
containded capital letters, then DROP command did not find a database
to drop.

tests/integration/functional/tools/test.sh

@@ -51,8 +51,9 @@ for testfun in ${tests}; do
 done
 
 on_exit
-psql -p $postgres_port -d postgres -v ON_ERROR_STOP=on -c "DROP DATABASE $DB_NAME";
+psql -p $postgres_port -d postgres -v ON_ERROR_STOP=on -c "DROP DATABASE \"$DB_NAME\"";
 
 echo "PASSED";
+trap - EXIT;
 exit 0;