get_iproto_port: remove duplicates

In some tests, instances have duplicate file descriptors on one socket,
which leads to abnormal termination of the test.

This patch removes duplicates to work around this problem.

lib/tarantool_server.py

@@ -1314,13 +1314,13 @@ def get_iproto_port(self):
                             socket.internal.SO_OPT[lvl].SO_REUSEADDR.iname,
                             val, len)
                         if val[0] > 0 then
-                            table.insert(res, addrinfo)
+                            res[addrinfo.port] = addrinfo
                         end
                     end
                 end
                 local l_sockets = {{}}
                 local con_timeout = 0.1
-                for i, s in ipairs(res) do
+                for _, s in pairs(res) do
                     con = socket.tcp_connect(s.host, s.port, con_timeout)
                     if con then
                         con:close()