Enable running unit test and coverage in py3.

- Migrate run_tests.sh to python3
- Running run_tests.sh in py2 is not supported.

Bug: 157392770
Test: ./run_test.sh
./run_test_py2.sh
atest --host acloud_test
atest --host acloud_test_py3

Change-Id: Ibf6a535f36c9ebd196b075eed092c10992f338eb
diff --git a/setup/host_setup_runner_test.py b/setup/host_setup_runner_test.py
index e435be6..111540e 100644
--- a/setup/host_setup_runner_test.py
+++ b/setup/host_setup_runner_test.py
@@ -17,7 +17,6 @@
 import tempfile
 import unittest
 import mock
-from six import b
 
 from acloud.internal.lib import driver_test_lib
 from acloud.internal.lib import utils
@@ -30,13 +29,13 @@
 class CuttlefishHostSetupTest(driver_test_lib.BaseDriverTest):
     """Test CuttlsfishHostSetup."""
 
-    LSMOD_OUTPUT = b("""nvidia_modeset        860160  6 nvidia_drm
+    LSMOD_OUTPUT = """nvidia_modeset        860160  6 nvidia_drm
 module1                12312  1
 module2                12312  1
 ghash_clmulni_intel    16384  0
 aesni_intel           167936  3
 aes_x86_64             20480  1 aesni_intel
-lrw                    16384  1 aesni_intel""")
+lrw                    16384  1 aesni_intel"""
 
     # pylint: disable=invalid-name
     def setUp(self):