fix(core-manager): process core persistence in a stream

[gurinderu]

Description

Use a receiver stream instream for the persistent task

Checklist

• The code follows the project's coding conventions and style guidelines.
• All tests related to the changes have passed successfully.
• Documentation has been updated to reflect the changes (if applicable).
• All new and existing unit tests have passed.
• I have self-reviewed my code and ensured its quality.
• I have added/updated necessary comments to aid understanding.

Reviewer Checklist

• Code has been reviewed for quality and adherence to guidelines.
• Tests have been reviewed and are sufficient to validate the changes.
• Documentation has been reviewed and is up to date.
• Any questions or concerns have been addressed.

[folex]

Tests passed here https://github.com/fluencelabs/nox/actions/runs/7992181006