Issue #8321 : Use the real Log4j2 SLF4J binding with a default config and publish Hop context as MDC

[rmannibucau]

Follow up of #8321 as a primary releasable step.
Rest will likely pop up later in a discussion/issue - but might later this year to get back enough hop OSS time ot evaluate the options in all env.

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[hansva]

does this replace #8320 ?

[rmannibucau]

@hansva it is more than this one has some agreement whereas the other didnt converge at all and this is already a huge step forward even if way less ambitious.

I'd keep the other opened mainly for history of the work with the note that we can need to take time to see if we make otel a first class citizen in hop superseeding current ad-hoc backbone and enabling the UI/server to integrate with an aggregator/collector rather than custom storage which doesn't work with all engines.
This can't be for a minor/patch release so this one is the intermediate step and we take time to refine a more global solution.
Means the other can be superseeded or not by another PR in a few months depending future discussions.