remove some more docker workflow remnants

.github/workflows/registry-overviews.yml

@@ -1,54 +0,0 @@
-name: Update Registry overviews
-
-env:
-  OWNER: ${{ github.repository_owner }}
-
-on:
-  push:
-    branches:
-      - main
-    paths:
-      - ".github/workflows/registry-overviews.yml"
-
-      - "README.md"
-      - "onbuild/README.md"
-      - "demo-image/README.md"
-      - "singleuser/README.md"
-  workflow_dispatch:
-
-jobs:
-  update-overview:
-    runs-on: ubuntu-latest
-    name: update-overview (${{matrix.image}})
-    if: github.repository_owner == 'jupyterhub'
-
-    steps:
-      - name: Checkout Repo ⚡️
-        uses: actions/checkout@v4
-
-      - name: Push README to Registry 🐳
-        uses: christian-korneck/update-container-description-action@d36005551adeaba9698d8d67a296bd16fa91f8e8 # v1
-        env:
-          DOCKER_USER: ${{ secrets.DOCKERHUB_USERNAME }}
-          DOCKER_PASS: ${{ secrets.DOCKERHUB_TOKEN }}
-        with:
-          destination_container_repo: ${{ env.OWNER }}/${{ matrix.image }}
-          provider: dockerhub
-          short_description: ${{ matrix.description }}
-          readme_file: ${{ matrix.readme_file }}
-
-    strategy:
-      matrix:
-        include:
-          - image: jupyterhub
-            description: "JupyterHub: multi-user Jupyter notebook server"
-            readme_file: README.md
-          - image: jupyterhub-onbuild
-            description: onbuild version of JupyterHub images
-            readme_file: onbuild/README.md
-          - image: jupyterhub-demo
-            description: Demo JupyterHub Docker image with a quick overview of what JupyterHub is and how it works
-            readme_file: demo-image/README.md
-          - image: singleuser
-            description: "single-user docker images for use with JupyterHub and DockerSpawner see also: jupyter/docker-stacks"
-            readme_file: singleuser/README.md

.github/workflows/test.yml

@@ -259,24 +259,3 @@ jobs:
           pytest -k "${{ matrix.subset }}" --maxfail=2 --cov=jupyterhub jupyterhub/tests
 
       - uses: codecov/codecov-action@v5
-
-  docker-build:
-    runs-on: ubuntu-22.04
-    timeout-minutes: 20
-
-    steps:
-      - uses: actions/checkout@v4
-
-      - name: build images
-        run: |
-          DOCKER_BUILDKIT=1 docker build -t jupyterhub/jupyterhub .
-          docker build -t jupyterhub/jupyterhub-onbuild onbuild
-          docker build -t jupyterhub/singleuser singleuser
-
-      - name: smoke test jupyterhub
-        run: |
-          docker run --rm -t jupyterhub/jupyterhub jupyterhub --help
-
-      - name: verify static files
-        run: |
-          docker run --rm -t -v $PWD/dockerfiles:/io jupyterhub/jupyterhub python3 /io/test.py