W-23735286- fix: use native fetch in schema update scripts

[soridalac]

What does this PR do?

Summary

• Replace node:https.get() with native fetch() + explicit User-Agent header in update-features.ts and update-settings.ts
• Add response validation (status check + JSON body check) and clear error
• Include features/settings that have accumulated since the script broke in April
• script broke since April: https://github.com/forcedotcom/sfdx-core/actions/runs/23975886079

Test plan

• Both scripts pass locally
• CI workflow passes: https://github.com/forcedotcom/sfdx-core/actions/runs/32074013293/job/95523138399

What issues does this PR fix or reference?

CLI related Issue: forcedotcom/cli#3617
@W-23735286@

[WillieRuemmele]

QA NOtes

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✅ : see passing build