Add Oracle Cloud to add_cloud_metadata

[rodrigc]

Describe the enhancement:

It would be good to add support for Oracle Cloud
to add_cloud_metadata. Currently this is not supported.

Describe a specific use case for the enhancement or feature:

I mentioned this in Elastic Support case 01464345, and Enhancement Request 19374 was created for this.

[botelastic]

This issue doesn't have a Team:<team> label.

[botelastic]

Hi!
We just realized that we haven't looked into this issue in a while. We're sorry!

We're labeling this issue as Stale to make it hit our filters and make sure we get back to it as soon as possible. In the meantime, it'd be extremely helpful if you could take a look at it as well and confirm its relevance. A simple comment with a nice emoji will be enough :+1.
Thank you for your contribution!