ci: run Renovate from asxpi/renovate

Renovate now runs from its own repository for every repo, with the
shared rules in its preset. Extend that preset here and keep only what
is specific to this repo (the Ansible var manager, the Paper JRE, the
runner and nix notes); drop the workflow that ran it for iac alone.

Assisted-by: Claude:opus-5-5

.forgejo/workflows/renovate.yaml

@@ -1,32 +0,0 @@
-name: renovate
-
-# Opens a PR per available version bump (image tags, restic, ...), with
-# the upstream release notes in the PR body. Configuration: renovate.json.
-#
-# Secrets: RENOVATE_TOKEN (Forgejo token of the renovate-bot user, a
-# collaborator with write access) and GH_COM_TOKEN (read-only github.com
-# token, only for fetching release notes; without it PRs have none).
-
-on:
-  schedule:
-    - cron: "17 5 * * *"
-  workflow_dispatch:
-
-jobs:
-  renovate:
-    runs-on: ubuntu-latest
-    container:
-      image: ghcr.io/renovatebot/renovate:44.236.2
-    steps:
-      - name: Run Renovate
-        env:
-          RENOVATE_PLATFORM: forgejo
-          RENOVATE_ENDPOINT: https://git.asxp.io/api/v1
-          RENOVATE_REPOSITORIES: asxpi/iac
-          RENOVATE_TOKEN: ${{ secrets.RENOVATE_TOKEN }}
-          RENOVATE_GITHUB_COM_TOKEN: ${{ secrets.GH_COM_TOKEN }}
-          RENOVATE_GIT_AUTHOR: "Renovate Bot <renovate-bot@noreply.git.asxp.io>"
-          RENOVATE_ONBOARDING: "false"
-          RENOVATE_REQUIRE_CONFIG: required
-          LOG_LEVEL: info
-        run: renovate