4.x: Use LevelChangePropagator in examples/logging/slf4j (#7737)

[Captain1653]

Description

References #7737

Thoughts:

1. I'm not sure, but it can be something like that. I've added org.slf4j:jul-to-slf4j, because it wasn't in the dependencies. I think, that it should be done.
2. It's little hard to understand, how to confirm, that the performance cost was mitigated :).

Questions:

1. I didn't add debug="true", because it wasn't added before. Should I add it?
2. Should I do the same things for logback-aot module? I think yes, but I can be wrong.

[romain-grecourt]

I'd say we want debug="true" as that us a short-hand for a best practice.
logback-aot should also be updated however you will need to triple check that it works well with native image.

[Captain1653]

I've found the "issue" with checkstyle.

Locally it doesn't check the rule NewlineAtEndOfFile, but CI does. Maybe I missed something.

I checked the checkstyle.xml and there is this rule.