[BUG] Misused the term and name of data source in the observability plugin.

[seraphjiang]

What is the bug?
The data source term used in this plugins is mis-used.

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

1. Go to '...'
   https://playground.opensearch.org/app/datasources#/

What is the expected behavior?
This should be called Data Adapter or Data Connector rather than Data Source.
There is already OSD build-in datasource feature launched in 2.4. we should either rename this to avoid confusion. or merge this into the build in data-source management, include move the storage to the .opensearch_dashboards index.

What is your host/environment?

• OS: All
• Version: all supported
• Plugins: Obserability

Do you have any screenshots?

[seraphjiang]

Hi @anirudha @brijos @kgcreative @elfisher

could we triage and build a consensus