Add rpm-vendor yum repository (#484)

Why: rpmbuilder's vendored third-party RPMs are moving from Gitea's RPM registry to the artifactapi rpm-vendor local repos. Managed AlmaLinux hosts need the matching yum repo to install them; this mirrors the existing rpm-internal repo and selects the per-EL-release repo via os.release.major.

Changes:
- Add rpm-vendor to profiles::yum::global::repos in hieradata/os/AlmaLinux/all_releases.yaml, pointing at .../api/v1/local/rpm-vendor-el<major>/ (el8/el9), gpgcheck disabled and mirrorlist absent, matching the rpm-internal repo definition.

Depends on terraform-artifactapi PR #6 (creates the rpm-vendor-el8/el9 repos).

Reviewed-on: #484
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>

hieradata/os/AlmaLinux/all_releases.yaml

@@ -85,6 +85,13 @@ profiles::yum::global::repos:
     baseurl: https://artifactapi.k8s.syd1.au.unkin.net/api/v1/local/rpm-internal/
     gpgcheck: false
     mirrorlist: absent
+  rpm-vendor:
+    name: rpm-vendor
+    descr: rpm-vendor repository
+    target: /etc/yum.repos.d/rpm-vendor.repo
+    baseurl: https://artifactapi.k8s.syd1.au.unkin.net/api/v1/local/rpm-vendor-el%{facts.os.release.major}/
+    gpgcheck: false
+    mirrorlist: absent
 
   # Additional repositories - default to absent, roles can override with ensure: present
   # FRRouting repositories