Remove visual samples index (#2607)

Removes VSI and all related infra. It has been replaced by [an index
page on
flutter.dev](https://docs.flutter.dev/reference/learning-resources)

Fixes:

#2582 
#2507 

## Pre-launch Checklist

- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I have added sample code updates to the [changelog].
- [x] I updated/added relevant documentation (doc comments with `///`).

.github/workflows/gh-pages.yml

@@ -1,38 +0,0 @@
-name: Deploy to GitHub Pages
-
-# Declare default permissions as read only.
-permissions: read-all
-
-on:
-  push:
-    branches:
-      - main
-jobs:
-  build-and-deploy:
-    permissions:
-      contents: write
-    runs-on: ubuntu-latest
-    if: github.repository == 'flutter/samples'
-
-    steps:
-      - name: Checkout
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
-        with:
-          submodules: true
-          fetch-depth: 0
-
-      - uses: subosito/flutter-action@e938fdf56512cc96ef2f93601a5a40bde3801046
-
-      - name: Init scripts
-        run: dart pub get
-        working-directory: web/_tool
-
-      - name: Build
-        run: dart run _tool/build_ci.dart
-        working-directory: web
-
-      - name: Deploy
-        uses: peaceiris/actions-gh-pages@4f9cc6602d3f66b9c108549d475ec49e8ef4d45e
-        with:
-          github_token: ${{ secrets.GITHUB_TOKEN }}
-          publish_dir: web/samples_index/public

.github/workflows/main.yml

@@ -37,17 +37,6 @@ jobs:
           channel: ${{ matrix.flutter_version }}
       - run: ./tool/flutter_ci_script_${{ matrix.flutter_version }}.sh
 
-  web-samples-index:
-    name: web/samples_index config check
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
-      - uses: subosito/flutter-action@e938fdf56512cc96ef2f93601a5a40bde3801046
-      - run: |
-          dart pub get
-          dart run grinder generate
-        working-directory: web/samples_index
-
   # android-build:
   #   runs-on: ubuntu-latest
   #   if: github.repository == 'flutter/samples'

.github/workflows/verify-web-demos.yml

@@ -1,36 +0,0 @@
-name: Verify web demos
-
-# Declare default permissions as read only.
-permissions: read-all
-
-on:
-  push:
-    branches: [ main ]
-  pull_request:
-    branches: [ main ]
-
-jobs:
-  verify-web-demos:
-    runs-on: ubuntu-latest
-    if: github.repository == 'flutter/samples'
-    strategy:
-      matrix:
-        flutter_version:
-          - stable
-          # TODO(johnpryan): https://github.com/flutter/samples/issues/1469
-          # - beta
-    steps:
-      - name: Checkout
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
-        with:
-          submodules: true
-          fetch-depth: 0
-      - uses: subosito/flutter-action@e938fdf56512cc96ef2f93601a5a40bde3801046
-        with:
-          channel: ${{ matrix.flutter_version }}
-      - name: Init scripts
-        run: dart pub get
-        working-directory: web/_tool
-      - name: Verify packages
-        run: dart run _tool/verify_packages.dart
-        working-directory: web