[chore] Update CODEOWNERS and bring oracle cloud metadata up to standards

[geekdave]

Description

Discussed with @dashpole and now that I am a codeowner for the oraclecloud area in the semconv repo, I am requesting codeowner status in collector-contrib as well.

Required "Ride-Along" Fixes

Making changes to metadata.yaml requires regenerating some files with mdatagen, which requires some further changes for the generating process itself to work. Seems that some standards have changed over the past few months, and the metadata.yaml file was no longer up to spec. When I tried to run mdatagen metadata.yaml I got an error:

status must be empty for subcomponents

Just as @paulojmdias discovered in a similar PR I also needed to make some changes to metadata.yaml to follow the conventions of some (but confusingly not all) other resource detection processors. I've followed suit by making similar changes in this PR, and now mdatagen cleanly generates files.

Also, somehow the descriptions for the attributes had been replaced with non-descriptive descriptions at some point recently, so I am restoring them.

Testing

Ran mdatagen successfully.