Fix a warning during make container

[Lyndon-Li]

Fix a warning during make container:

 1 warning found (use docker --debug to expand):                                                                                                             
 - UndefinedVar: Usage of undefined variable '$GOPROXY' (line 58)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 58.99%. Comparing base (a9b5dbc) to head (fa7fca8). Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #8338 +/- ## ======================================= Coverage 58.99% 58.99% ======================================= Files 367 367 Lines 38847 38847 ======================================= Hits 22918 22918 Misses 14467 14467 Partials 1462 1462 ```

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