fix clang-tidy failing on master (#25121)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/25121
Turns out there is a more idiomatic way to use azure variables. This
also fixes clang-tidy failing on master
Test Plan: Imported from OSS
Differential Revision: D16994595
Pulled By: suo
fbshipit-source-id: 5c5b1b47ced57cff85c4302cde43ff8c8c3f54c0
