[chore][receiver/googlecloudpubsub] update to cloud.google.com/go/pub…

[alexvanboxel]

Description

Update to the cloud.google.com/go/pubsub/v2 package to keep the Renovate bot happy.

This PR is scoped to the receiver/googlepubsubreceiver

Link to tracking issue

This PR fixes renovate trying to upgrade but can't because it requires code changes:
#42871

And remove the Pubsub part in the combined deprecation fix PR:
#41646

Testing

Changed existing test to match the new API.

Documentation

No documentation change required.

[alexvanboxel]

/label receiver/googlepubsubreceiver waiting-for-code-owners

[crobert-1]

Thanks for taking care of this, @alexvanboxel! Do you think adding a changelog would be helpful here since it's a major version upgrade, or is the expectation that this does not impact users in any way? (If there's a chance this impacts users, I'd tend to lean towards adding a changelog just in case)

[alexvanboxel]

Thanks for taking care of this, @alexvanboxel! Do you think adding a changelog would be helpful here since it's a major version upgrade, or is the expectation that this does not impact users in any way? (If there's a chance this impacts users, I'd tend to lean towards adding a changelog just in case)

I think the risk is low because I use the pure gRPC contracts as the client itself hides too much. If it needs a changelog, I should do one for the exporter as well. What should the change type be... enhancement?

[crobert-1]

What should the change type be... enhancement?

I think enhancement would make the most sense. If you're up for it, I'd say we may as well add them. There's no harm in adding a changelog here, and it may be helpful.

[alexvanboxel]

Rebased and added an extra commit with the 2 changelogs for the exporter and receiver.