Fix existing broker tests to pretend Apple Silicon

The new Intel-Mac gate reads platform.machine(). Existing tests patch
sys.platform to darwin but ran on x86_64 CI runners, so the gate disabled
the broker and four tests failed. Patch platform.machine() to arm64 so
those Mac scenarios are hardware-independent.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: ashok672

tests/test_application.py

@@ -1014,6 +1014,8 @@ def test_client_id_should_be_a_valid_scope(self):
 
 
 @patch("sys.platform", new="darwin")  # Pretend running on Mac.
+@patch("msal.application.platform.machine", new=Mock(return_value="arm64"))
+# Pretend Apple Silicon, because broker is not supported on Intel-based Macs.
 @patch("msal.authority.tenant_discovery", new=Mock(return_value={
     "authorization_endpoint": "https://contoso.com/placeholder",
     "token_endpoint": "https://contoso.com/placeholder",
@@ -1056,6 +1058,8 @@ def test_should_fallback_when_pymsalruntime_failed_to_initialize_broker(self):
 
 
 @patch("sys.platform", new="darwin")  # Pretend running on Mac.
+@patch("msal.application.platform.machine", new=Mock(return_value="arm64"))
+# Pretend Apple Silicon, because broker is not supported on Intel-based Macs.
 @patch("msal.authority.tenant_discovery", new=Mock(return_value={
     "authorization_endpoint": "https://contoso.com/placeholder",
     "token_endpoint": "https://contoso.com/placeholder",