test: remove unused test (#4703)

## Explanation

We have a mock and a test that is not used anymore. It still passed the
CI, but actually doesn't test anything.

## References

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* Fixes #12345
* Related to #67890
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## Changelog

### `@metamask/profile-sync-controller`

- **REMOVED**: unused mock function.

## 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 highlighted breaking changes using the "BREAKING" category
above as appropriate

packages/profile-sync-controller/src/controllers/user-storage/UserStorageController.test.ts

@@ -22,6 +22,7 @@ import {
   MOCK_STORAGE_KEY,
   MOCK_STORAGE_KEY_SIGNATURE,
 } from './__fixtures__/mockStorage';
+import * as AccountsUserStorageModule from './accounts/user-storage';
 import encryption from './encryption/encryption';
 import type {
   GetUserStorageAllFeatureEntriesResponse,
@@ -1185,6 +1186,11 @@ describe('user-storage/user-storage-controller - saveInternalAccountToUserStorag
       };
     };
 
+    const mapInternalAccountToUserStorageAccountMock = jest.spyOn(
+      AccountsUserStorageModule,
+      'mapInternalAccountToUserStorageAccount',
+    );
+
     const { messengerMocks } = await arrangeMocks();
     const controller = new UserStorageController({
       messenger: messengerMocks.messenger,
@@ -1202,9 +1208,7 @@ describe('user-storage/user-storage-controller - saveInternalAccountToUserStorag
       MOCK_INTERNAL_ACCOUNTS.ONE[0] as InternalAccount,
     );
 
-    expect(
-      messengerMocks.mockAccountsGetAccountByAddress,
-    ).not.toHaveBeenCalled();
+    expect(mapInternalAccountToUserStorageAccountMock).not.toHaveBeenCalled();
   });
 
   it('returns void if account syncing feature flag is disabled', async () => {
@@ -1431,10 +1435,6 @@ function mockUserStorageMessenger(options?: {
 
   const mockAccountsUpdateAccountMetadata = jest.fn().mockResolvedValue(true);
 
-  const mockAccountsGetAccountByAddress = jest
-    .fn()
-    .mockResolvedValue(MOCK_INTERNAL_ACCOUNTS.ONE[0]);
-
   jest.spyOn(messenger, 'call').mockImplementation((...args) => {
     // Creates the correct typed call params for mocks
     type CallParams = {
@@ -1512,17 +1512,9 @@ function mockUserStorageMessenger(options?: {
       return mockAccountsUpdateAccountMetadata(args.slice(1));
     }
 
-    if (actionType === 'AccountsController:getAccountByAddress') {
-      return mockAccountsGetAccountByAddress();
-    }
-
-    const exhaustedMessengerMocks = (action: never) => {
-      throw new Error(
-        `MOCK_FAIL - unsupported messenger call: ${action as string}`,
-      );
-    };
-
-    return exhaustedMessengerMocks(actionType);
+    throw new Error(
+      `MOCK_FAIL - unsupported messenger call: ${actionType as string}`,
+    );
   });
 
   return {
@@ -1539,7 +1531,6 @@ function mockUserStorageMessenger(options?: {
     mockAuthPerformSignOut,
     mockKeyringAddNewAccount,
     mockAccountsUpdateAccountMetadata,
-    mockAccountsGetAccountByAddress,
     mockAccountsListAccounts,
   };
 }