Fixed and added tests for node reload_secure_settings and usage APIs.

[dblock]

Description

• Fixed response from /_nodes/.../reload_secure_settings.
• Fixed responses from /_nodes/.../usage.

Issues Resolved

Part of #663.

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[github-actions]

Spec Test Coverage Analysis

Total	Tested
528	393 (74.43 %)

[github-actions]

Changes Analysis

Commit SHA: bcc099c
Comparing To SHA: 4615564

API Changes

Summary

└─┬Components
  ├──[➕] schemas (53814:7)
  ├─┬nodes.usage___Metric
  │ └──[➕] enum (55221:11)
  ├─┬nodes.usage___NodeUsage
  │ ├──[➖] required (55233:11)❌ 
  │ └──[➖] required (55234:11)❌ 
  ├─┬nodes._common___NodeReloadResult
  │ ├──[➕] anyOf (53807:7)
  │ ├──[➕] anyOf (53814:7)
  │ ├──[➖] oneOf (53807:7)❌ 
  │ └──[➖] oneOf (54244:7)❌ 
  └─┬nodes._common___NodeReloadError
    ├──[➖] required (53814:11)❌ 
    ├──[➖] type (53807:13)❌ 
    ├──[➖] properties (53809:9)❌ 
    ├──[➖] properties (53811:9)❌ 
    ├──[➕] allOf (53814:7)
    └──[➕] allOf (53809:11)

Document Element	Total Changes	Breaking Changes
components	14	8

• ❌ BREAKING Changes: 8 out of 14
• Removals: 8
• Additions: 6
• Breaking Removals: 8

Report

The full API changes report is available at: https://github.com/opensearch-project/opensearch-api-specification/actions/runs/12014616804/artifacts/2234174679

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