`load_schema` race

These lines result in an index exception, trying to connect to the instance that actively applies DDL due to the race with the tarantool object creation:

https://github.com/tarantool/tarantool-python/blob/28310fc4e927c77d3be75e98360bf3b09f72482a/tarantool/connection.py#L1409-L1410

As these two fetches are non-transactional, the second one can return an index for space that is not fetched at the first fetch, resulting in:

Traceback (most recent call last):
  File "/python/lib/python3.11/site-packages/tarantool/connection.py", line 1097, in connect
    self.load_schema()
  File "/python/lib/python3.11/site-packages/tarantool/connection.py", line 1316, in load_schema
    self.schema.fetch_index_all()
  File "/python/lib/python3.11/site-packages/tarantool/schema.py", line 377, in fetch_index_all
    SchemaIndex(row, self.schema[row[0]])

从 tarantool/connection.py 中 1409-1410 附近的链接行开始，然后跟踪 load_schema 到 tarantool/schema.py，并在失败的调用处检查 fetch_index_all。复现 Tarantool 对象并发创建的情况，并检查两次非事务 fetch 如何相互作用。当 load_schema 不再引发索引异常并处理一致的 schema 时，即表示完成。