fix(clique step_service): remove needless Arc

[niklasad1]

No description provided.

[dvdplm]

So I think this is good stuff, but you need the changes from #10689 and even then stop() is not getting called because Drop for Client fails (here).

Curious though: how do you know the Arc isn't needed? I find it hard to prove that an Arc is not needed (sure, I guess in this case you know that no code passes the StepService to diff threads?). How do you go about it?

[niklasad1]

It shouldn't compile then because Clique is wrapped in an Arc directly in the constructor, which doesn't provide mutation unless risky Arc::get_mut(). Thus, I think stop() never is called otherwise it shouldn't compile.

Basically, this is all wrong either use drop or change to stop(&self) and wrap step_service in an Mutex/RwLock.

Closing in favor of #10683