[Azure pipelines] Too high CMake 4.x version

I created a PR regarding toggling ETW https://github.com/microsoft/DirectXShaderCompiler/pull/7274, my attention took Nix Linux_Clang_Release job and failure at configuration step - it appears latest workflow runner took recent CMake 4.0 which banned a lot of old policies still present in DXC build system.

2025-03-29T07:27:57.0741231Z CMake Warning (dev) at /usr/local/share/cmake-4.0/Modules/FindPackageHandleStandardArgs.cmake:430 (message):

hence it generated errors at configuration step

2025-03-29T07:27:44.1835242Z CMake Error at CMakeLists.txt:26 (cmake_policy):
2025-03-29T07:27:44.1835689Z Policy CMP0051 may not be set to OLD behavior because this version of CMake
2025-03-29T07:27:44.1836135Z no longer supports it. The policy was introduced in CMake version 3.1.0,
2025-03-29T07:27:44.1837000Z and use of NEW behavior is now required.
2025-03-29T07:27:44.1837293Z
2025-03-29T07:27:44.1837475Z Please either update your CMakeLists.txt files to conform to the new
2025-03-29T07:27:44.1837806Z behavior or use an older version of CMake that still supports the old
2025-03-29T07:27:44.1838037Z behavior. Run cmake --help-policy CMP0051 for more information.

2025-03-29T07:28:01.1773504Z CMake Error at tools/clang/CMakeLists.txt:1 (cmake_minimum_required):
2025-03-29T07:28:01.1775286Z Compatibility with CMake < 3.5 has been removed from CMake.
2025-03-29T07:28:01.1775369Z
2025-03-29T07:28:01.1775538Z Update the VERSION argument value. Or, use the ... syntax
2025-03-29T07:28:01.1775768Z to tell CMake that the project requires at least but has been updated
2025-03-29T07:28:01.1775957Z to work with policies introduced by or earlier.
2025-03-29T07:28:01.1776026Z
2025-03-29T07:28:01.1776189Z Or, add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to try configuring anyway.
2025-03-29T07:28:01.1776273Z
2025-03-29T07:28:01.1776313Z
2025-03-29T07:28:01.1867560Z -- Configuring incomplete, errors occurred!

and failed the job; maybe one could consider using 3.x with workflows or update build system?

Start with CMakeLists.txt and tools/clang/CMakeLists.txt, then reproduce the configuration failure in the Nix Linux_Clang_Release job using the linked build log. Compare the project’s policy and minimum-version settings with the runner’s CMake version; done means the job configures successfully with an explicitly chosen CMake version or updated policies.