Use DiscoverRunner's logger for logging when running checks

[Chris Jerdonek]

Currently, when a logger is passed to DiscoverRunner, there is at least one case where DiscoverRunner's logger isn't used for logging log-like messages. This is when DiscoverRunner runs the check command (code ​here) and displays a message like the "System check identified no issues ...."

While there is some overlap with ticket #21429 (which is about logging for all commands), I think this ticket can be kept separate because it can be done independently, and in particular either before or after that ticket is complete.

I do have at least one idea of how this ticket can be addressed pretty simply, and in a way that would help make tangible forward progress on #21429. I can add a comment to that ticket explaining the approach in order to keep followers of that ticket in the loop.

[Mariusz Felisiak]

I do have at least one idea of how this ticket can be addressed pretty simply, ...

Sounds good, I'd be happy to review the patch.

[Ahmed Ibrahim]

What pops in mind is to allow call_command to use external loggers via params, this may also help the code that uses stdout directly