Refactor and improve testing of log package

What does this MR do?

Follow up for !1020 (merged). Adds missing testing for some of the features, and does a little refactorization for this occasion.

Why was this MR needed?

~"technical debt" and ~backstage. Just wanted to move our code coverage metric a little higher again 😉

Are there points in the code the reviewer needs to double check?

Built on top of !1020 (merged) so needs to wait for it to be merged This is done 😉

Does this MR meet the acceptance criteria?

• Documentation created/updated
• Added tests for this feature/bug
• In case of conflicts with master - branch was rebased

What are the relevant issue numbers?