fix(sdk-core): rollback api-mock.ts to use deprecate fetch client fro…

…m core (#2212)

## Proposed change

Rollback `api-mock.ts` to use deprecate fetch client from core.
This change will be part of #2117.

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## Related issues

- 🔗  Related to: #2117 

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packages/@ama-sdk/schematics/schematics/typescript/core/openapi-codegen-typescript/src/main/resources/typescriptFetch/spec/api-mock.mustache

@@ -1,6 +1,6 @@
 {{#apiInfo}}
 import { type ApiClient, isApiClient } from '@ama-sdk/core';
-import { ApiFetchClient, type BaseApiFetchClientConstructor } from '@ama-sdk/client-fetch';
+import { ApiFetchClient, type BaseApiFetchClientConstructor } from '@ama-sdk/core';
 
 import * as api from '../api';