Mark network peering routes fields GA

[rileykarson]

Pre-work for hashicorp/terraform-provider-google#5007 so I don't need version guards for my test

Release Note Template for Downstream PRs (will be copied)

compute: made the `google_compute_network_peering` routes fields available in GA

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff
Terraform Beta: Diff

[modular-magician]

Hi! I'm the modular magician, I work on Magic Modules.
I see that this PR has already had some downstream PRs generated. Any open downstreams are already updated to your most recent commit, a4cc2ee.

Pull request statuses

No diff detected in terraform-google-conversion.
No diff detected in Ansible.
No diff detected in Inspec.

New Pull Requests

I built this PR into one or more new PRs on other repositories, and when those are closed, this PR will also be merged and closed.
depends: hashicorp/terraform-provider-google-beta#1650
depends: hashicorp/terraform-provider-google#5419