Companion PR for 'Simplify `NativeExecutionDispatch` and remove the...

Companion PR for 'Simplify `NativeExecutionDispatch` and remove the `native_executor_instance!`'  (9562) (#3643)

* Companion PR

* Add test executors

* Change comment to doc comment

* Update node/test/service/src/lib.rs

* Improve comments

* update Substrate

Co-authored-by: parity-processbot <>
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