[BUG] Unable to create Transform Job using UI for index patterns

[tandonks]

What is the bug?
The issue appears to be a bug in the OpenSearch console when creating a transform job for an index pattern. The API call to fetch sample data for the index pattern to create groups and define aggregations is failing, causing the transform job creation to fail with the "Invalid index name" error.

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

1. Go to Transform page on Opensearch dashboards
2. Click on Create transform
3. In source index, try using an index-pattern
4. See error when trying to create

What is the expected behavior?
A clear and concise description of what you expected to happen.

What is your host/environment?

• OS: 2.18

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.

[shiv0408]

Thanks for creating this @tandonks