Delete cmd/mdatagen from contrib

[atoulme]

Component(s)

cmd/mdatagen

Describe the issue you're reporting

cmd/mdatagen is moving to opentelemetry-collector.

Perform the following actions:

• Deprecate the cmd/mdatagen with a "Deprecated" comment - [cmd/mdatagen] prepare deprecation #30498
• Publish a new version of the package with the deprecation
• Sync up the code changes from contrib to core
• Delete the code

[github-actions]

Pinging code owners:

• cmd/mdatagen: @dmitryax

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[atoulme]

This issue is blocked by open-telemetry/opentelemetry-collector#9281

[atoulme]

I filed open-telemetry/opentelemetry-collector#9436 to move any changes that were only made in contrib to core.

[atoulme]

I can't see https://pkg.go.dev/search?q=mdatagen&m=package showing contrib mdatagen, so I think we can delete the code without deprecating it for a release first.

[adrielp]

Just wanted to mention this for general awareness. For those that maintain distributions and version lock mdatagen as part of their build process (we do through tools.go 🤚🏼) it'll break the build on version updates if we don't update the location. Really not a big problem, we'd catch it through the workflows, but might be good to just shout it a little louder to the community for other distro maintainers so they're aware in advance.

[atoulme]

I have announced this move in the SIG meeting yesterday https://docs.google.com/document/d/1r2JC5MB7GupCE7N32EwGEXs9V_YIsPgoFiLP4VWVMkE/edit#bookmark=id.uzx4ruz8h632 - would you like to announce this change in the CNCF slack @adrielp ? Is there anything else we need to do to announce this change?

[adrielp]

@atoulme , I'd be totally happy to help do that if that's the approach y'all want to take 😊 . I do think it'd be a good idea for those in slack that don't attend the SIGs. The SIG is how I find out about it and found it very helpful. The only reason I commented on this was because I thought maybe there was another method of communication y'all use to communicate with distro maintainers, etc. Slack was definitely the avenue I thought of because I've seen messages in the various otel channels in the past for calls to action on system stability, etc.

[atoulme]

Please go ahead and make noise. This change is coming soon.

[povilasv]

Question, should new PRs go to this repository or the opentelemetry-collector now?

Reference: #29769

[atoulme]

Probably opentelemetry-collector by default