[BUG] dlq object should include the dynamic index runtime value instead of the literal value in pipeline configuration

Describe the bug
A clear and concise description of what the bug is.

given the following snippet in pipeline YAML:

opensearch:
    index: "${/index}"
    dlq:
          s3:
            bucket: ...

The dlq object will end up having the following key-value:

"failedData":{"index":"${/index}"

in which /failedData/index value is the literal value in the pipeline config.

To Reproduce
Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
The expected behavior should be the runtime value extracted from individual event:

"failedData":{"index":"<<runtime value from individual event under /index json path>>"

Screenshots
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Environment (please complete the following information):

• OS: [e.g. Ubuntu 20.04 LTS]
• Version [e.g. 22]

Additional context
Add any other context about the problem here.

Start by reproducing the issue with the pipeline YAML shown, using a dynamic /index value in an individual event and inspecting the resulting failedData/index value in the DLQ object. Trace the pipeline's DLQ handling from the opensearch configuration and verify that done means failedData/index contains the event's runtime value rather than the literal "${/index}".