Remove --no-use-pep517 test

This option is gone.

tests/functional/test_install_reqs.py

@@ -13,7 +13,6 @@
     _create_test_package_with_subdirectory,
     create_basic_sdist_for_package,
     create_basic_wheel_for_package,
-    make_wheel,
     need_svn,
     requirements_file,
 )
@@ -918,26 +917,3 @@ def test_config_settings_local_to_package(
     assert "--verbose" not in simple3_args
     simple2_args = simple2_sdist.args()
     assert "--verbose" not in simple2_args
-
-
-def test_nonpep517_setuptools_import_failure(script: PipTestEnvironment) -> None:
-    """Any import failures of `setuptools` should inform the user both that it's
-    not pip's fault, but also exactly what went wrong in the import."""
-    # Install a poisoned version of 'setuptools' that fails to import.
-    name = "setuptools_poisoned"
-    module = """\
-raise ImportError("this 'setuptools' was intentionally poisoned")
-"""
-    path = make_wheel(name, "0.1.0", extra_files={"setuptools.py": module}).save_to_dir(
-        script.scratch_path
-    )
-    script.pip("install", "--no-index", path)
-
-    result = script.pip_install_local("--no-use-pep517", "simple", expect_error=True)
-    nice_message = (
-        "ERROR: Can not execute `setup.py`"
-        " since setuptools failed to import in the build environment"
-    )
-    exc_message = "ImportError: this 'setuptools' was intentionally poisoned"
-    assert nice_message in result.stderr
-    assert exc_message in result.stderr