[processor/oracleclouddetector] Add Oracle "Realm" attribute to RDP

[geekdave]

Description

Add the vendor-specific realm attribute to the Oracle Cloud resource detection processor.

Note: This is a redo of closed PR #45890 which had some unrelated changes that I split into another PR: #46006

Link to tracking issue

Fixes #44408

Testing

Unit Tests

Updated auto-generated unit tests, as well as test fixture in metadata_test.go.

e2e Tests

Updated tests, and mock server data to include realm. (Thanks to @paulojmdias for implementing the oraclecloud e2e tests in #45598 !)

Manual Pipeline Tests on real OKE (Oracle Kubernetes Engine) cluster

Enabled debug exporter and verified that oracle_cloud.realm attribute shows up, using expected vendor-prefix matching semantic conventions.

Used Prometheus exporter, and verified that downstream enriched metric labels show up as oracle_cloud_realm, with expected replacement of . -> _.

Documentation

Updated generated docs.

Semconv notes

I've added oracle_cloud.realm as a vendor-prefixed attribute in a newly-created area in the semantic-conventions repo. However, it's currently not possible to reference semantic conventions from the resource_attributes section of a component's metadata.yaml, so we can't use it yet, and it's hardcoded for now (as are the other metric names in that file).

Support for using the conventions in metadata.yaml has an open issue in the collector repo, and still appears to be actively discussed.

I will keep an eye on the upstream issue. I've created issue #45920 to use the Semantic Conventions for the Oracle Cloud RDP attribute names once the upstream support is available.

cc @tonychoe

[paulojmdias]

Config schemas are out of date, please run "make generate-schemas" and commit the changes in this PR.