chore: parallelize presubmit unit test runs with pytest-xdist

PiperOrigin-RevId: 823199807

Author: speedstorm1

.kokoro/presubmit/unit_3-10.cfg

@@ -9,5 +9,5 @@ env_vars: {
 # Run unit tests in parallel, splitting up by file
 env_vars: {
     key: "PYTEST_ADDOPTS"
-    value: "-n=auto --dist=loadscope"
+    value: "-n=8 --dist=loadscope"
 }

.kokoro/presubmit/unit_3-11.cfg

@@ -9,5 +9,5 @@ env_vars: {
 # Run unit tests in parallel, splitting up by file
 env_vars: {
     key: "PYTEST_ADDOPTS"
-    value: "-n=auto --dist=loadscope"
+    value: "-n=8 --dist=loadscope"
 }

.kokoro/presubmit/unit_3-12.cfg

@@ -9,5 +9,5 @@ env_vars: {
 # Run unit tests in parallel, splitting up by file
 env_vars: {
     key: "PYTEST_ADDOPTS"
-    value: "-n=auto --dist=loadscope"
+    value: "-n=8 --dist=loadscope"
 }

.kokoro/presubmit/unit_3-9.cfg

@@ -9,5 +9,5 @@ env_vars: {
 # Run unit tests in parallel, splitting up by file
 env_vars: {
     key: "PYTEST_ADDOPTS"
-    value: "-n=auto --dist=loadscope"
+    value: "-n=8 --dist=loadscope"
 }

noxfile.py

@@ -204,7 +204,6 @@ def default(session):
     # Run py.test against the unit tests.
     session.run(
         "py.test",
-        "--quiet",
         f"--junitxml=unit_{session.python}_sponge_log.xml",
         "--cov=google",
         "--cov-append",