Rename interop-as-a-unit-test "intraop"

It's been confusing that these tests have been called "interop" but
are not actually tests of interoperation.

src/python/grpcio_tests/tests/interop/_insecure_interop_test.py → src/python/grpcio_tests/tests/interop/_insecure_intraop_test.py

@@ -35,13 +35,13 @@ import unittest
 import grpc
 from src.proto.grpc.testing import test_pb2
 
-from tests.interop import _interop_test_case
+from tests.interop import _intraop_test_case
 from tests.interop import methods
 from tests.interop import server
 
 
-class InsecureInteropTest(
-    _interop_test_case.InteropTestCase,
+class InsecureIntraopTest(
+    _intraop_test_case.IntraopTestCase,
     unittest.TestCase):
 
   def setUp(self):

src/python/grpcio_tests/tests/interop/_interop_test_case.py → src/python/grpcio_tests/tests/interop/_intraop_test_case.py

@@ -32,7 +32,7 @@
 from tests.interop import methods
 
 
-class InteropTestCase(object):
+class IntraopTestCase(object):
   """Unit test methods.
 
   This class must be mixed in with unittest.TestCase and a class that defines

src/python/grpcio_tests/tests/interop/_secure_interop_test.py → src/python/grpcio_tests/tests/interop/_secure_intraop_test.py

@@ -35,15 +35,15 @@ import unittest
 import grpc
 from src.proto.grpc.testing import test_pb2
 
-from tests.interop import _interop_test_case
+from tests.interop import _intraop_test_case
 from tests.interop import methods
 from tests.interop import resources
 
 _SERVER_HOST_OVERRIDE = 'foo.test.google.fr'
 
 
-class SecureInteropTest(
-    _interop_test_case.InteropTestCase,
+class SecureIntraopTest(
+    _intraop_test_case.IntraopTestCase,
     unittest.TestCase):
 
   def setUp(self):

src/python/grpcio_tests/tests/tests.json

 [
   "health_check._health_servicer_test.HealthServicerTest",
-  "interop._insecure_interop_test.InsecureInteropTest",
-  "interop._secure_interop_test.SecureInteropTest",
+  "interop._insecure_intraop_test.InsecureIntraopTest",
+  "interop._secure_intraop_test.SecureIntraopTest",
   "protoc_plugin._python_plugin_test.PythonPluginTest",
   "protoc_plugin._split_definitions_test.SameCommonTest",
   "protoc_plugin._split_definitions_test.SameSeparateTest",