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.

Written by the indexing model from the issue text.