chore: Migrate test fixture to messenger (#6961)

## Explanation

A test fixture used by the package `@metamask/profile-sync-controller`
has been migrated to use the new `@metamask/messenger` package, in
praration for the `Messenger` being removed from
`@metamask/base-controller`.

## References

Relates to #5626

## Checklist

- [x] I've updated the test suite for new or updated code as appropriate
- [x] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [x] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/contributing.md#updating-changelogs),
highlighting breaking changes as necessary
- [x] I've prepared draft pull requests for clients and consumer
packages to resolve any breaking changes

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Switches the contact-syncing test fixture to use @metamask/messenger
with namespaced Messenger and updated types.
> 
> - **Tests (contact syncing)**:
> - Replace `@metamask/base-controller` `Messenger` with
`@metamask/messenger` `Messenger` in `__fixtures__/test-utils.ts`.
> - Add `MockAnyNamespace` typing and initialize `Messenger` with
`MOCK_ANY_NAMESPACE`.
> - Update generic types (`ActionConstraint`, `EventConstraint`) and
imports to align with `@metamask/messenger` API.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
caf2a47. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: Gudahtt

packages/profile-sync-controller/src/controllers/user-storage/contact-syncing/__fixtures__/test-utils.ts

@@ -5,8 +5,12 @@ import type {
 import type {
   ActionConstraint,
   EventConstraint,
-} from '@metamask/base-controller';
-import { Messenger as MessengerImpl } from '@metamask/base-controller';
+  MockAnyNamespace,
+} from '@metamask/messenger';
+import {
+  MOCK_ANY_NAMESPACE,
+  Messenger as MessengerImpl,
+} from '@metamask/messenger';
 
 import { MOCK_LOCAL_CONTACTS } from './mockContacts';
 
@@ -32,14 +36,18 @@ export function mockUserStorageMessengerForContactSyncing(options?: {
     clearEventSubscriptions: unknown;
     registerInitialEventPayload: jest.Mock;
   };
-  baseMessenger: MessengerImpl<ActionConstraint, EventConstraint>;
+  baseMessenger: MessengerImpl<
+    MockAnyNamespace,
+    ActionConstraint,
+    EventConstraint
+  >;
   mockAddressBookList: jest.Mock;
   mockAddressBookSet: jest.Mock;
   mockAddressBookDelete: jest.Mock;
   contactsUpdatedFromSync: AddressBookEntry[]; // Track contacts that were updated via sync
 } {
   // Start with a fresh messenger mock
-  const baseMessenger = new MessengerImpl();
+  const baseMessenger = new MessengerImpl({ namespace: MOCK_ANY_NAMESPACE });
 
   // Contacts that are synced/updated will be stored here for test inspection
   const contactsUpdatedFromSync: AddressBookEntry[] = [];