fix the tescase for bug #855616 (memcached_space must not be configured)

test/box_memcached/off.result

@@ -54,7 +54,7 @@ configuration:
   space[0].index[1].key_field[0].fieldno: "1"
   space[0].index[1].key_field[0].type: "STR"
 ...
-tarantool_box -c /home/avd/tarantool/tarantool/test/box_memcached/tarantool_memcached_bad.cfg
-/home/avd/tarantool/tarantool/mod/box/tarantool_box: can't load config:
+tarantool_box -c tarantool_memcached_bad.cfg
+tarantool_box: can't load config:
  - Space 0 is already used as memcached_space.
 

test/box_memcached/off.test

@@ -2,6 +2,7 @@
 #
 
 import os
+import sys
 
 print """
 # Bug #855616:
@@ -18,7 +19,9 @@ exec admin "show configuration"
 # stop current server
 server.stop()
 # start server with memcached space conflict
+sys.stdout.push_filter("(/\S+)+/tarantool", "tarantool")
 server.test_option("-c " + os.path.join(os.getcwd(), "box_memcached/tarantool_memcached_bad.cfg"))
+sys.stdout.pop_filter()
 
 # restore default server
 server.stop()