docs: add ingest-pipeline report for v2.19.0

[tkykenmt]

Summary

This PR adds documentation for the verbose_pipeline parameter introduced in OpenSearch v2.19.0 for debugging search pipelines.

Changes

Release Report

• Created docs/releases/v2.19.0/features/opensearch/ingest-pipeline.md
  • Documents the new verbose_pipeline parameter
  • Explains processor execution tracking (input/output, duration, status)
  • Includes usage examples and error handling behavior

Feature Report Update

• Updated docs/features/opensearch/opensearch-search-pipeline.md
  • Added v2.19.0 to Change History
  • Added PR #16843 to Pull Requests table
  • Added related issues (#14745, #16705)
  • Added debugging documentation link

Release Index

• Updated docs/releases/v2.19.0/index.md to include "Ingest Pipeline"

Key Feature Details

The verbose_pipeline parameter enables detailed debugging of search pipeline execution:

• Tracks processor name, tag, duration, status
• Captures input/output data for each processor
• Logs errors without interrupting search execution
• Works with default, specific, and temporary pipelines

References

• PR: Add verbose pipeline parameter to output each processor's execution details opensearch-project/OpenSearch#16843
• Issue: [Feature Request] Support a verbose/debugging param in search pipelines opensearch-project/OpenSearch#14745
• RFC: [RFC] Tracking Search Pipeline Execution opensearch-project/OpenSearch#16705