docs: `alibaba cloud` (#14772)
The [provider
page](https://python.langchain.com/docs/integrations/providers/alibabacloud_opensearch)
holds the vector store information. The [Chat
example](https://python.langchain.com/docs/integrations/chat/pai_eas_chat_endpoint)
was incorrectly sorted in the navbar because of the wrong file name.
- Recreated a provide page
- Added missed links and descriptions
- Compound information about vector store from two pages into one
- Fixed file name
