fix(metallb): deploy MetalLB with a non-BGP Cilium CNI (#692)

- Correct the Deploy metallb manifest/pool when condition so MetalLB is
  installed whenever kube-vip does not own the VIP range and Cilium BGP
  is disabled
- The previous guard (cilium_bgp is not defined or cilium_iface is not
  defined) skipped MetalLB whenever cilium_iface was set, breaking the
  cilium + MetalLB scenario
- Use cilium_bgp | default(false) | bool to stay safe when Cilium vars are
  not in scope (#644) while still deploying MetalLB for non-BGP Cilium
- Retry the converge-side MetalLB resource wait so a transient kube API
  ServiceUnavailable does not abort the converge play
- Add a regression test that evaluates both when conditions across flannel,
  calico, non-BGP cilium, BGP cilium, and kube-vip scenarios

ci: skip CI for Dependabot pull requests

- Add an actor guard to the CI workflow jobs so automatic Dependabot PRs
  do not consume the shared self-hosted runner
- Dependabot CI runs need maintainer approval instead of auto-running

.pre-commit-config.yaml

@@ -84,6 +84,15 @@ repos:
         language: system
         pass_filenames: false
         files: ^roles/k3s_server/tasks/metallb\.yml$|^\.github/scripts/test-metallb-remote-read\.sh$
+      - id: metallb-deploy-condition-test
+        name: MetalLB deploy condition test
+        entry: python3 .github/scripts/test-metallb-deploy-condition.py
+        language: python
+        additional_dependencies:
+          - Jinja2>=3.1
+          - PyYAML
+        pass_filenames: false
+        files: ^roles/k3s_server/tasks/main\.yml$|^roles/k3s_server_post/tasks/main\.yml$|^\.github/scripts/test-metallb-deploy-condition\.py$ # noqa yaml[line-length]
       - id: default-interface-test
         name: default interface test
         entry: python3 .github/scripts/test-default-interface.py