[chore] [exporter/clickhouse] add warnings to metadata

[SpencerTorres]

Description:
Resolves #32041

Also allows marking this exporter as completed on #19172

Declare in the metadata.yaml that this exporter has no warnings.
Because there are no warnings, there is no change to the README.md after running make generate

[atoulme]

That's the default value, I'm not sure that needs to be explicit? Is there a practical advantage I am missing?

[SpencerTorres]

That's the default value, I'm not sure that needs to be explicit? Is there a practical advantage I am missing?

The intent was to show that we have reviewed #19172 and explicitly say that we have no warnings.

If referencing #32041 is good enough to mark our component as complete then we can cancel this PR. I did see some other components provide an empty array. Kind of like null vs undefined in JavaScript, this PR makes it clear we have none-- or that we haven't forgotten to review it

[atoulme]

OK. Maybe there's something else we need to do there to make it clear that warnings were reviewed, as this won't change README. I am filing open-telemetry/opentelemetry-collector#9894 to follow up.

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[github-actions]

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