Add forgotten space:drop()

test/box/admin.result

@@ -271,3 +271,6 @@ test_box_fiber_info();
 ---
 - box.fiber.info() is ok
 ...
+box.space[0]:drop();
+---
+...

test/box/admin.test.lua

@@ -163,3 +163,4 @@ end;
 test_box_info();
 test_box_slab_info();
 test_box_fiber_info();
+box.space[0]:drop();