Deduplicate metadata for structured logging

[swsnr]

Closes #1537

[swsnr]

@sdroege This adds a test for the log impl and removes the duplicated metadata by avoiding the log_structured! macro.

[swsnr]

@sdroege I'd like to point out that changed the pipeline to hopefully include the log feature so as to run the new test on Github actions. However, since the pipeline didn't pass in the first place (it's even broken on master), and is somewhat complex, the change to the Github workflow is more of an educated guess than actually understanding what I did there :innocent:

[sdroege]

since the pipeline didn't pass in the first place (it's even broken on master)

Yeah packages are automatically updated there and one update requires changes in the tests. I hope to get to fixing this some time this week. Sorry for the trouble!

[swsnr]

@sdroege No worries, didn't affect me much, as I can just run tests locally. Just wanted to point the one part of this PR I'm not entirely sure about :innocent:

[sdroege]

It looks correct. I'll fix it if it isn't :)

[swsnr]

Thanks for merging :pray: