fix fast_replica.lua for out of source builds

test/replication/lua/fast_replica.lua

 
 function join(inspector, n)
+    local path = os.getenv('TARANTOOL_SRC_DIR')
     for i=1,n do
         local rid = tostring(i)
         os.execute('mkdir -p tmp')
-        os.execute('cp ../replication/replica.lua ./tmp/replica'..rid..'.lua')
+        os.execute('cp '..path..'/test/replication/replica.lua ./tmp/replica'..rid..'.lua')
         os.execute('chmod +x ./tmp/replica'..rid..'.lua')
-        inspector:cmd("create server replica"..rid.." with rpl_master=default, script='./var/tmp/replica"..rid..".lua'")
+        local out_dir = box.cfg.wal_dir
+        inspector:cmd("create server replica"..rid.." with rpl_master=default, script='"..out_dir.."/../tmp/replica"..rid..".lua'")
         inspector:cmd("start server replica"..rid)
     end
 end