Test and fix remaining /_ingest paths.

[dblock]

Description

• Add s parameter to /_ingest/processor/grok.
• Fix /_ingest/pipeline/{id}/_simulate response doc/_source field schema.

Part of #663.

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[github-actions]

Changes Analysis

Commit SHA: 16a4805
Comparing To SHA: 7e08a43

API Changes

Summary

├─┬Paths
│ └─┬/_ingest/processor/grok
│   └─┬GET
│     └──[➕] parameters (21667:13)❌ 
└─┬Components
  ├──[➕] parameters (21667:7)
  └─┬ingest.simulate___DocumentSimulation
    └─┬_source
      └──[🔀] additionalProperties (51995:33)❌ 

Document Element	Total Changes	Breaking Changes
components	2	1
paths	1	1

• ❌ BREAKING Changes: 2 out of 3
• Modifications: 1
• Additions: 2
• Breaking Modifications: 1
• Breaking Additions: 1

Report

The full API changes report is available at: https://github.com/opensearch-project/opensearch-api-specification/actions/runs/11999916007/artifacts/2230332325

API Coverage

	Before	After	Δ
Covered (%)	599 (58.67 %)	599 (58.67 %)	0 (0 %)
Uncovered (%)	422 (41.33 %)	422 (41.33 %)	0 (0 %)
Unknown	42	42	0

[github-actions]

Spec Test Coverage Analysis

Total	Tested
528	384 (72.73 %)