Init `deploy_stats` in nameserver

`deploy_stats` has not been inited in [InitGlobalVarTable](https://github.com/4paradigm/OpenMLDB/blob/main/src/nameserver/name_server_impl.cc#L10574)

The issue points to a missing initialization of `deploy_stats` in the `InitGlobalVarTable` function at line 10574 in src/nameserver/name_server_impl.cc. First, examine the surrounding code to understand the structure of `deploy_stats` and its type. Then, add the appropriate initialization, likely setting it to a default value like zero or an empty state. Verify the change by building the project and running any related tests for the nameserver component.

索引モデルが issue の本文から書いたものです。