Enable RPC sample generation for the "corner case" APIs

These are the packages we skipped for RPC sample generation in #4720

- [ ] google-cloud-compute-v1: Some sample functions have no body except for `OK()`. Not clear why.
- [ ] google-cloud-logging-v2: The "parent" field on the `ListLogEntriesRequest` is a `repeated string` (for listing resources from different parents at the same time) field instead of a `string` field, which is non AIP compliant. We need to check that the `parent` field is a `string`.
- [ ] google-cloud-oslogin-v1: There's a `common` package and some of the resources with CRUD operations are defined in that common package.

Note we also skippep part of Pub/Sub, but that's still under development and we are tracking Pub/Sub sample generation on #4018