[DRS] task source/dest db_type validation removed

[anton-sidelnikov]

Summary of the Pull Request

PR Checklist

• [x] Refers to: #2317
• [ ] Tests added/passed.
• [x] Documentation updated.
• [x] Schema updated.
• [x] Release notes added.

[otc-zuul[bot]]

Build succeeded. https://zuul.otc-service.com/t/eco/buildset/139bd46ea2364fc5a4fd2841fb274adf

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