BREAKING: Remove messaging.consumer.id, make messaging.client_id generic

[pyohannes]

Fixes #2015

Changes

Based on discussions in the messaging workgroup and in issue #2015, this PR proposes to remove messaging.consumer.id, and to replace both messaging.kafka.client_id and messaging.rocketmq.client_id with a generic messaging.client_id.

messaging.consumer.id is defined to always be set to the client_id of the used messaging system, except for Kafka, where it was defined to be a combination of messaging.kafka.client_id and messaging.kafka.consumer.group, or just the latter if messaging.kafka.client_id is not available. With this definition, the semantics of consumer.id are different between messaging systems, and even different for different Kafka scenarios.

The proposed messaging.client_id has consistent semantics ("an unique client id, when it is available"), and can be used instead of messaging.consumer.id in almost all cases.

In addition to have consistent semantics, this also simplifies the semantic conventions, as instead of

messaging.consumer.id
messaging.kafka.client_id
messaging.rocketmq.client_id

there is now just:

messaging.client_id.

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 7 days.

[github-actions]

Closed as inactive. Feel free to reopen if this PR is still being worked on.

[pyohannes]

@Oberon00 Could you please have a look whether this resolves #2015, and possibly approve?

[Oberon00]

Thanks, I think this should indeed solve #2015.

[carlosalberto]

CHANGELOG entry, please ;)

[pyohannes]

CHANGELOG entry, please ;)

@carlosalberto Done.