ci: add deployment environments for all deployment workflows

Code posting the link to comments is removed
as deployment URLs are directly visible in the UI.

.github/workflows/test-and-deploy-ipv4only.yaml

@@ -16,6 +16,9 @@ jobs:
     name: deploy on staging-ipv4.testrun.org, and run tests
     runs-on: ubuntu-latest
     timeout-minutes: 30
+    environment:
+      name: staging-ipv4.testrun.org
+      url: https://staging-ipv4.testrun.org/
     concurrency:
       group: ci-ipv4-${{ github.workflow }}-${{ github.ref }}
       cancel-in-progress: ${{ !contains(github.ref, '$GITHUB_REF') }}