Move blocking error logging to executor thread

[Arooba-git]

Hi! :)

Thank you for this project.

This PR fixes a blocking call that happens when logging error as detected by BlockHound:

We re-ran the tests to ensure the fix is non-intrusive.

[vietj]

if you have issue with logging, you should configure it to log differently, i.e with an asynchronous logger. pehraps also you should avoid using java logger, https://dzone.com/articles/asynchronous-logging-with-log4j-2

[vietj]

also that is a blocking call, but it does not report whether this call actually blocks in practice.

I see you using BlockHound and reporting issue accross the codebase to use an executor (that is not closed in your PR) and I think you should before reporting a PR discuss each case separately, there might be case where it is appropriare and case where it is not depending on the context / situation. It is not possible to use a dedicated executor to solve the situation everytime you see BlockFound reporting something.

Vert.x has a mechanism to detect blocking, and it detect blocking when it actually is a problem and not when it can potentially block.