Remove the test for old namespace package based on pkg_resource

It won't work when the package is removed anyway

Author: Pierre-Sassoulas

tests/test_manager.py

@@ -117,16 +117,6 @@ def test_ast_from_namespace_pkgutil(self) -> None:
     def test_ast_from_namespace_pkg_resources(self) -> None:
         self._test_ast_from_old_namespace_package_protocol("pkg_resources")
 
-    def test_identify_old_namespace_package_protocol(self) -> None:
-        # Like the above cases, this package follows the old namespace package protocol
-        # astroid currently assumes such packages are in sys.modules, so import it
-        # pylint: disable-next=import-outside-toplevel
-        import tests.testdata.python3.data.path_pkg_resources_1.package.foo as _  # noqa
-
-        self.assertTrue(
-            util.is_namespace("tests.testdata.python3.data.path_pkg_resources_1")
-        )
-
     def test_submodule_homonym_with_non_module(self) -> None:
         self.assertFalse(
             util.is_namespace("tests.testdata.python3.data.parent_of_homonym.doc")