fix: mock delegationCredential in getRoutedUsers test to prevent flaky worker shutdown errors (#28603)

* fix: mock delegationCredential in getRoutedUsers test to prevent flaky worker shutdown errors

The getRoutedUsers.test.ts file only tests the pure sync function
getRoutedUsersWithContactOwnerAndFixedUsers, but importing getRoutedUsers.ts
triggers a heavy transitive import chain:

  getRoutedUsers.ts
  -> @calcom/app-store/delegationCredential
  -> _utils/getCalendar
  -> calendar.services.generated (all calendar services)
  -> CalendarService.ts -> ics/tsdav

Sometimes the vitest worker finishes tests and shuts down before all async
module resolution completes, causing:
  Error: [vitest-worker]: Closing rpc while "fetch" was pending

Mock @calcom/app-store/delegationCredential to cut off the import chain
since the tested function doesn't use it.

* Clean up comments in getRoutedUsers.test.ts

Removed comments about mocking delegationCredential to improve code clarity.

packages/features/users/lib/getRoutedUsers.test.ts

@@ -1,5 +1,4 @@
-import { describe, it, expect, vi } from "vitest";
-
+import { describe, expect, it, vi } from "vitest";
 import { getRoutedUsersWithContactOwnerAndFixedUsers } from "./getRoutedUsers";
 
 vi.mock("@calcom/prisma", () => {
@@ -8,6 +7,12 @@ vi.mock("@calcom/prisma", () => {
   };
 });
 
+vi.mock("@calcom/app-store/delegationCredential", () => {
+  return {
+    enrichHostsWithDelegationCredentials: vi.fn().mockResolvedValue([]),
+  };
+});
+
 describe("getRoutedUsersWithContactOwnerAndFixedUsers", () => {
   const users = [
     { id: 1, email: "user1@example.com", isFixed: false },