[BUG] On initial load the index management plugin page is empty

[BionIT]

What is the bug?
On the initial load of the plugin page, it shows empty with no errors
http://localhost:5601/app/opensearch_index_management_dashboards#/

However, enter the following url with subpath, would show the page, but the default is local cluster http://localhost:5601/app/opensearch_index_management_dashboards#/index-policies

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

1. yarn start to spin off osd and the plugin
2. Click on 'index management'
3. See empty page

What is the expected behavior?
The plugin should show a landing page with subpath /index-policies, similar to https://playground.opensearch.org/app/opensearch_index_management_dashboards#/index-policies?from=0&search=&size=20&sortDirection=desc&sortField=id

Default data source is introduced and set by data source picker as call back, the default data source id should be used instead of local cluster as default

What is your host/environment?

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

[BionIT]

@RamakrishnaChilaka while pulling from main, I found the issue described above, could you help to resolve?

[RamakrishnaChilaka]

Thanks Lu, for reporting the bug. I acknowledge that this is indeed a bug, this should be fixed with #1039

[RamakrishnaChilaka]

@BionIT, closing this as #1039 PR is merged and I have verified that issue is fixed. Kindly, reopen the issue if you find that issue is not fixed.