Re-enable tests (IronLanguages#2063)

Author: slozier

tests/IronPython.Tests/Cases/IronPythonCasesManifest.ini

@@ -203,6 +203,3 @@ RunCondition=$(IS_POSIX) # Module resource is Posix-specific
 [IronPython.modules.system_related.test_sys_getframe]
 IsolationLevel=PROCESS # https://github.com/IronLanguages/ironpython3/issues/489
 FullFrames=true
-
-[IronPython.modules.system_related.test_sys]
-RunCondition=NOT $(IS_NETCOREAPP) # https://github.com/IronLanguages/ironpython3/issues/2057

tests/suite/test_stdconsole.py

@@ -7,7 +7,7 @@
 import sys
 import unittest
 
-from iptest import IronPythonTestCase, is_cli, is_netcoreapp21, is_posix, run_test, skipUnlessIronPython, is_netcoreapp
+from iptest import IronPythonTestCase, is_cli, is_netcoreapp21, is_posix, run_test, skipUnlessIronPython
 
 if is_cli:
     import clr
@@ -404,7 +404,7 @@ def test_isatty(self):
         finally:
             self.batfile = hideDefaultBatch
 
-    @unittest.skipIf(not is_cli or is_netcoreapp, "https://github.com/IronLanguages/ironpython3/issues/2057")
+    @skipUnlessIronPython()
     def test_cp35263(self):
         script = """
 import warnings