Fix macOS CI V8 OOM: remove --single-process now that launchctl asuser fixes Mach ports

--single-process was added in cc0217e as a workaround for Mach port
rendezvous failures (child processes could not look up the server in
the CI bootstrap domain).  b643615 fixed the root cause by running
tests via "launchctl asuser", so --single-process is no longer needed.

With --single-process still present, V8 fails to reserve a contiguous
virtual memory CodeRange for each in-process renderer isolate
(V8 process OOM: Failed to reserve virtual memory for CodeRange),
causing osr_test to error out after step 4.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: linesight

unittests/main_test.py

@@ -176,16 +176,15 @@ def test_main(self):
             # Suppress the GNOME Keyring unlock prompt on desktop sessions.
             switches["password-store"] = "basic"
         if MAC:
-            # macOS CI runners run in a background bootstrap domain where
-            # MachPortRendezvousServer lookups fail for child processes.
-            # The CI workflow runs tests via "launchctl asuser" to place the
-            # browser process in the user's login session bootstrap domain.
-            # These switches add further subprocess-spawn reduction as guards.
+            # The CI workflow runs tests via "launchctl asuser" so the browser
+            # process lives in the user login session bootstrap domain and child
+            # processes can look up MachPortRendezvousServer.
+            # cefpython does not ship a chrome-sandbox binary.
             switches["no-sandbox"] = ""
+            # No real GPU available on macOS CI runners.
             switches["disable-gpu"] = ""
             switches["disable-gpu-compositing"] = ""
             switches["in-process-gpu"] = ""
-            switches["single-process"] = ""
             # Prevent macOS keychain authorization prompts during init
             # (matches CEF's own test infrastructure on macOS).
             switches["use-mock-keychain"] = ""

unittests/osr_test.py

@@ -136,14 +136,13 @@ def test_osr(self):
             switches["disable-features"] = "StorageServiceOutOfProcess"
             switches["enable-features"] = "NetworkServiceInProcess"
         if MAC:
-            # macOS CI runners run in a background bootstrap domain where
-            # MachPortRendezvousServer lookups fail for child processes.
-            # The CI workflow runs tests via "launchctl asuser" to place the
-            # browser process in the user's login session bootstrap domain.
-            # These switches add further subprocess-spawn reduction as guards.
+            # The CI workflow runs tests via "launchctl asuser" so the browser
+            # process lives in the user login session bootstrap domain and child
+            # processes can look up MachPortRendezvousServer.
+            # cefpython does not ship a chrome-sandbox binary.
             switches["no-sandbox"] = ""
+            # No real GPU available on macOS CI runners.
             switches["in-process-gpu"] = ""
-            switches["single-process"] = ""
             # Prevent macOS keychain authorization prompts during init
             # (matches CEF's own test infrastructure on macOS).
             switches["use-mock-keychain"] = ""