Revert "fixup! Explicit backend @ test_all_extras_and_all_build_deps[backtracking]"

This reverts commit ce53764.

Author: webknjaz

tests/test_cli_compile.py

@@ -3477,10 +3477,6 @@ def test_compile_build_targets_setuptools_no_wheel_dep(
     (tmp_path / "pyproject.toml").write_text(
         dedent(
             """
-            [build-system]
-            requires = ["setuptools"]
-            build-backend = "setuptools.build_meta"
-
             [project]
             name = "foo"
             version = "0.0.1"