Index Upgrade API specs and tests for them

[Tokesh]

Description

API specs and tests for upgrade api
And marking them deprecated
GET /_upgrade
POST /_upgrade
GET /{index}/_upgrade
POST /{index}/_upgrade

Issues Resolved

[#663]

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[github-actions]

Spec Test Coverage Analysis

Total	Tested
528	414 (78.41 %)

[github-actions]

Changes Analysis

Commit SHA: 481692a
Comparing To SHA: 962452c

API Changes

Summary

├─┬Paths
│ ├─┬/{index}/_upgrade
│ │ ├─┬GET
│ │ │ ├─┬Responses
│ │ │ │ └─┬200
│ │ │ │   └──[➕] content (29211:11)
│ │ │ └─┬Extensions
│ │ │   └──[➕] x-version-deprecated (12223:29)
│ │ └─┬POST
│ │   ├──[➕] requestBody (26686:7)❌ 
│ │   ├─┬Responses
│ │   │ └─┬200
│ │   │   └──[➕] content (29452:11)
│ │   └─┬Extensions
│ │     └──[➕] x-version-deprecated (12244:29)
│ └─┬/_upgrade
│   ├─┬GET
│   │ ├─┬Responses
│   │ │ └─┬200
│   │ │   └──[➕] content (29211:11)
│   │ └─┬Extensions
│   │   └──[➕] x-version-deprecated (9489:29)
│   └─┬POST
│     ├──[➕] requestBody (26686:7)❌ 
│     ├─┬Responses
│     │ └─┬200
│     │   └──[➕] content (29452:11)
│     └─┬Extensions
│       └──[➕] x-version-deprecated (9509:29)
└─┬Components
  ├──[➕] requestBodies (26686:7)
  ├──[➕] schemas (50136:7)
  ├──[➕] schemas (49099:7)
  ├──[➕] schemas (50145:7)
  ├──[➕] schemas (50120:7)
  └──[➕] schemas (49147:7)

Document Element	Total Changes	Breaking Changes
paths	10	2
components	6	0

• ❌ BREAKING Changes: 2 out of 16
• Additions: 16
• Breaking Additions: 2

Report

The full API changes report is available at: https://github.com/opensearch-project/opensearch-api-specification/actions/runs/12104083308/artifacts/2257912337

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

[dblock]

Let's find out when this was deprecated and why and put a real version number here. What message do you get (aka how do you know it's deprecated)? Look for it in https://github.com/opensearch-project/opensearch and narrow down the commit / PR that did it.

[dblock]

Probably good to flip this one with the triggering of an upgrade so we can get actual results and check schema.

[Tokesh]

If I understood you correctly, then I have corrected

[Tokesh]

Let's find out when this was deprecated and why and put a real version number here. What message do you get (aka how do you know it's deprecated)? Look for it in https://github.com/opensearch-project/opensearch and narrow down the commit / PR that did it.

Hello! I found that, the _upgrade API was deprecated in Elasticsearch 7.10, which is precisely the version OpenSearch was forked from.

And I've also added tests for:
GET /_upgrade
POST /_upgrade

[dblock]

Note that this is not an /{index} API and should go in its own tests/default/_core/upgrade.yaml. I'll merge now, but appreciate it being split in a future PR.