Memory leak in zk_client.cc

[wuxiaobai24]

Bug Description
zoo_get_children will allocate memory in struct String_vector, we need to use deallocate_String_vector to free memory by ourself.

OpenMLDB/src/zk/zk_client.cc

Line 498 in 4403222

int ret = zoo_get_children(zk_, path.c_str(), 0, &data);

OpenMLDB/src/zk/zk_client.cc

Line 523 in 4403222

int ret = zoo_get_children(zk_, nodes_root_path_.c_str(), 0, &data);

There are two place to call zoo_get_children, I think we can add deallocate_String_vector(&data) at line 505 and line 530 to fix this bug.

Expected Behavior

Steps to Reproduce