[chore] Prepare v1.25.0 release

[lmolkova]

Changes

• Updates spec version from 1.26 to 1.31 (hence all the spec link changes)
• Merges auto and manual changelogs

Merge requirement checklist

• CONTRIBUTING.md guidelines followed.
• Change log entry added, according to the guidelines in When to add a changelog entry.
  • If your PR does not need a change log, start the PR title with [chore]
• schema-next.yaml updated with changes to existing conventions.

[jack-berg]

If you're interested, I can run semantic-conventions-java against this branch and spot check it for any issues. Don't have time today, but can do it tomorrow.

[lmolkova]

If you're interested, I can run semantic-conventions-java against this branch and spot check it for any issues. Don't have time today, but can do it tomorrow.

@jack-berg that'd be great, thanks!

I run the new compat-check tool and here's the list of breaking changes I see.
(The tool will be part of CI after this release and we'll not allow them anymore).

$ docker run --rm -v c:/repo/semantic-conventions/model:/source -v  c/repo/semantic-conventions/docs:/spec  otel/semconvgen:0.24.0 -f /source --continue-on-validation-errors compatibility --previous-version 1.24.0

Found 8 compatibility issues:
        enum attribute member 'messaging.system.azure_eventgrid' was removed
        enum attribute member 'messaging.system.azure_eventhubs' was removed
        enum attribute member 'messaging.system.azure_servicebus' was removed
        metric 'http.client.request.time_in_queue' was removed
        metric 'messaging.deliver.duration' was removed
        metric 'messaging.deliver.messages' was removed
        metric 'system.processes.count' was removed
        metric 'system.processes.created' was removed

In theory we can fix them, but I believe no one (including Java) generates metrics yet, so I'd rather not deprecate them this last time.

I'd also let messaging.system.azure_ die in silence because they were never supported by Azure SDK instrumentations or any other instrumentation I'm aware of.
If you feel strongly about keeping them, I could live with them being deprecated.

Let me know if you see any other incompatibilities or want to fix these ones.

[jack-berg]

Here's a draft of what the changes look like in semantic-conventions-java: open-telemetry/semantic-conventions-java#61

Looks good to me!