draft: light-testnet [do not merge]

[gacevicljubisa]

Checklist

• [ ] I have read the coding guide.
• [ ] My change requires a documentation update, and I have done it.
• [ ] I have added tests to cover my changes.
• [ ] I have filled out the description and linked the related issues.

Description

Open API Spec Version Changes (if applicable)

Motivation and Context (Optional)

Related Issue (Optional)

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