Update message handler supervisor to watch children

[4e6]

Pull Request Description

close #11248

Changelog:

• update: bind message handler supervisor lifetime to the message handler lifetime

Important Notes

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• The documentation has been updated, if necessary.
• All code follows the
  Scala,
  Java,
  TypeScript,
  and
  Rust
  style guides. In case you are using a language not listed above, follow the Rust style guide.
• Unit tests have been written where possible.