fix(tests): align CI tests with recent security hardening (#31470)

Four recent security PRs landed on main with stale/missing test updates,
breaking 4 test shards on every subsequent PR's CI run:

- test_discord_bot_auth_bypass.py (PR #30742 c3caca658):
  DISCORD_ALLOWED_ROLES no longer bypasses _is_user_authorized.
  Inverted 3 tests to assert the new (correct) behavior: role config
  alone does NOT authorize at the gateway layer.

- test_msgraph_webhook.py (PR #30169 4ca77f105):
  adapter.is_connected is a @property, not a method. Test was calling
  it with () after the connect() change; TypeError: 'bool' is not
  callable. Removed the parens.

- test_feishu_approval_buttons.py (PR #30744 bdb97b857):
  Card-action callbacks now go through _allow_group_message
  authorization. 3 tests in TestCardActionCallbackResponse didn't
  populate adapter._allowed_group_users so the operator's open_id got
  rejected. Added the allowlist setup to each test, matching the
  existing pattern in test_returns_card_for_approve_action.

Also raise tolerance on test_wait_for_process_kills_subprocess_on_keyboardinterrupt:
the SIGTERM → 3s TimeoutStopSec → SIGKILL → reap chain can exceed 10s
under loaded xdist (40 workers). Bumped _wait_for_pgid_exit timeout
10→30s and worker join timeout 5→15s. Passes 100% in isolation
already; this just makes it tolerant of CI-host load.

Validation: 270/270 tests pass across the 5 affected files.

tests/gateway/test_msgraph_webhook.py

@@ -77,7 +77,8 @@ class TestMSGraphValidationHandshake:
         adapter = MSGraphWebhookAdapter(PlatformConfig(enabled=True, extra={}))
         connected = await adapter.connect()
         assert connected is False
-        assert adapter.is_connected() is False
+        # is_connected is a @property on the base adapter, not a method.
+        assert adapter.is_connected is False
 
     @pytest.mark.anyio
     async def test_validation_token_echo_on_get(self):