Disable two aio tests for aarch64 for strange platform behavior (#26409)

* Disable two aio tests for aarch64 for strange platform behavior

* Make sanity test happy

src/python/grpcio_tests/tests_aio/unit/channel_argument_test.py

@@ -97,6 +97,8 @@ class TestChannelArgument(AioTestBase):
 
     @unittest.skipIf(platform.system() == 'Windows',
                      'SO_REUSEPORT only available in Linux-like OS.')
+    @unittest.skipIf('aarch64' in platform.machine(),
+                     'SO_REUSEPORT needs to be enabled in Core\'s port.h.')
     async def test_server_so_reuse_port_is_set_properly(self):
 
         async def test_body():

src/python/grpcio_tests/tests_aio/unit/connectivity_test.py

@@ -15,6 +15,7 @@
 
 import asyncio
 import logging
+import platform
 import threading
 import time
 import unittest
@@ -37,6 +38,8 @@ class TestConnectivityState(AioTestBase):
     async def tearDown(self):
         await self._server.stop(None)
 
+    @unittest.skipIf('aarch64' in platform.machine(),
+                     'The transient failure propagation is slower on aarch64')
     async def test_unavailable_backend(self):
         async with aio.insecure_channel(UNREACHABLE_TARGET) as channel:
             self.assertEqual(grpc.ChannelConnectivity.IDLE,