Update docker.elastic.co/elasticsearch/elasticsearch Docker tag to v9.2.1 (#137924)

This PR contains the following updates:

| Package | Update | Change | |---|---|---| |
[docker.elastic.co/elasticsearch/elasticsearch](https://www.elastic.co/products/elasticsearch)
([source](https://redirect.github.com/elastic/elasticsearch)) | patch |
`9.2.0` -> `9.2.1` |

---

### Release Notes

<details> <summary>elastic/elasticsearch
(docker.elastic.co/elasticsearch/elasticsearch)</summary>

###
[`v9.2.1`](https://redirect.github.com/elastic/elasticsearch/releases/tag/v9.2.1):
Elasticsearch 9.2.1

[Compare
Source](https://redirect.github.com/elastic/elasticsearch/compare/v9.2.0...v9.2.1)

Downloads: https://elastic.co/downloads/elasticsearch Release notes:
https://www.elastic.co/docs/release-notes/elasticsearch#elasticsearch-9.2.1-release-notes

</details>

---

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x-pack/qa/repository-old-versions-compatibility/src/javaRestTest/resources/README.md

@@ -35,10 +35,10 @@ docker run -d --name es \
 -v ${SHARED_FOLDER}/data:/usr/share/elasticsearch/data \
 -v ${SHARED_FOLDER}/snapshots:/usr/share/elasticsearch/snapshots \
 --env "discovery.type=single-node" \
-docker.elastic.co/elasticsearch/elasticsearch:9.2.0
+docker.elastic.co/elasticsearch/elasticsearch:9.2.1
 
 // Version 6
-docker.elastic.co/elasticsearch/elasticsearch:9.2.0
+docker.elastic.co/elasticsearch/elasticsearch:9.2.1
 ```
 
 ### Create Index Version 5