[BUG] Integrations doesn't create objects using selected data source

[joshuali925]

What is the bug?
With data sources enabled, dashboards can connect to multiple data sources. Integrations supports MDS through #2051.

But when i create an integration with a data source selected, the objects created still references the local cluster

How can one reproduce the bug?
Steps to reproduce the behavior:

1. Go to integrations
2. create integration with a data source that's not local cluster
3. go to the index pattern created from the integration
4. See Data Source Connection is empty

What is the expected behavior?
the index pattern should have datasource id in its references, and for visualizations that do not use index pattern, they should also have data source reference in their definition

What is your host/environment?

• OS: [e.g. iOS]
• Version [e.g. 22] main
• Plugins

Do you have any screenshots?
If applicable, add screenshots to help explain your problem.

Do you have any additional context?
Add any other context about the problem.