🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

noxfile.py

@@ -48,7 +48,7 @@
 UNIT_TEST_EXTRAS: List[str] = []
 UNIT_TEST_EXTRAS_BY_PYTHON: Dict[str, List[str]] = {}
 
-SYSTEM_TEST_PYTHON_VERSIONS: List[str] = ["3.9"]
+SYSTEM_TEST_PYTHON_VERSIONS: List[str] = ["3.8"]
 SYSTEM_TEST_STANDARD_DEPENDENCIES: List[str] = [
     "mock",
     "pytest",
@@ -217,7 +217,6 @@ def install_systemtest_dependencies(session, *constraints):
     # Exclude version 1.52.0rc1 which has a known issue.
     # See https://github.com/grpc/grpc/issues/32163
     session.install("--pre", "grpcio!=1.52.0rc1")
-    session.install("pytest-xdist")
 
     session.install(*SYSTEM_TEST_STANDARD_DEPENDENCIES, *constraints)
 
@@ -283,7 +282,7 @@ def system(session, database_dialect):
     if system_test_exists:
         session.run(
             "py.test",
-            "-n=12",
+            "--quiet",
             f"--junitxml=system_{session.python}_sponge_log.xml",
             system_test_path,
             *session.posargs,
@@ -295,7 +294,7 @@ def system(session, database_dialect):
     if system_test_folder_exists:
         session.run(
             "py.test",
-            "-n=12",
+            "--quiet",
             f"--junitxml=system_{session.python}_sponge_log.xml",
             system_test_folder_path,
             *session.posargs,

samples/samples/noxfile.py

@@ -230,7 +230,6 @@ def _session_tests(
 
     session.run(
         "pytest",
-        "-n=12",
         *(PYTEST_COMMON_ARGS + session.posargs + concurrent_args),
         # Pytest will return 5 when no tests are collected. This can happen
         # on travis where slow and flaky tests are excluded.