Fixed content-type of GET /_plugins/_observability/_local/stats.

[dblock]

Description

• Fixed content-type of GET /_plugins/_observability/_local/stats.
• Removed tenant from ObservabilityObject being required.
• Added missing observability tests.

Issues Resolved

Part of #663.

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[github-actions]

Changes Analysis

Commit SHA: 9e8fd5a
Comparing To SHA: 415bad4

API Changes

Summary

├─┬Paths
│ └─┬/_plugins/_observability/_local/stats
│   └─┬GET
│     ├──[🔀] description (5069:20)
│     ├─┬Responses
│     │ └─┬200
│     │   ├──[➕] content (30374:11)
│     │   └──[➖] content (30374:11)❌ 
│     └─┬Extensions
│       └──[🔀] x-version-added (5068:24)
└─┬Components
  └─┬observability._common___ObservabilityObject
    └──[➖] required (56129:11)❌ 

Document Element	Total Changes	Breaking Changes
paths	4	1
components	1	1

• ❌ BREAKING Changes: 2 out of 5
• Modifications: 2
• Removals: 2
• Additions: 1
• Breaking Removals: 2

Report

The full API changes report is available at: https://github.com/opensearch-project/opensearch-api-specification/actions/runs/12248168208/artifacts/2297435634

API Coverage

	Before	After	Δ
Covered (%)	606 (59.35 %)	606 (59.35 %)	0 (0 %)
Uncovered (%)	415 (40.65 %)	415 (40.65 %)	0 (0 %)
Unknown	43	43	0

[github-actions]

Spec Test Coverage Analysis

Total	Tested
536	439 (81.9 %)