DEV: Remove unused "migration-tests" from stable branch (#28144)

It's currently not working and not needed on the stable branch

.github/dependabot.yml

@@ -78,11 +78,3 @@ updates:
       types:
         patterns:
           - "@types/*"
-#  - package-ecosystem: "bundler"
-#    directory: "migrations/config/gemfiles/convert"
-#    schedule:
-#      interval: "weekly"
-#      day: "wednesday"
-#      time: "10:00"
-#      timezone: "Europe/Vienna"
-#    versioning-strategy: "increase"

.github/workflows/migration-tests.yml

@@ -1,179 +0,0 @@
-name: Migration Tests
-
-on:
-  pull_request:
-    paths:
-      - ".github/workflows/migration-tests.yml"
-      - "migrations/**"
-  push:
-    branches:
-      - main
-      - stable
-    paths:
-      - ".github/workflows/migration-tests.yml"
-      - "migrations/**"
-
-concurrency:
-  group: migration-tests-${{ format('{0}-{1}', github.head_ref || github.run_number, github.job) }}
-  cancel-in-progress: true
-
-permissions:
-  contents: read
-
-jobs:
-  tests:
-    if: github.event_name == 'pull_request' || github.repository != 'discourse/discourse-private-mirror'
-    name: Tests with Ruby ${{ matrix.ruby }}
-    runs-on: 'ubuntu-latest'
-    container: discourse/discourse_test:slim
-    timeout-minutes: 20
-
-    env:
-      RAILS_ENV: test
-      PGUSER: discourse
-      PGPASSWORD: discourse
-
-    strategy:
-      fail-fast: false
-
-      matrix:
-        ruby: ["3.2"]
-
-    steps:
-      - name: Set working directory owner
-        run: chown root:root .
-
-      - uses: actions/checkout@v4
-        with:
-          fetch-depth: 1
-
-      - name: Setup Git
-        run: |
-          git config --global user.email "ci@ci.invalid"
-          git config --global user.name "Discourse CI"
-
-      - name: Start redis
-        run: |
-          redis-server /etc/redis/redis.conf &
-
-      - name: Start Postgres
-        run: |
-          chown -R postgres /var/run/postgresql
-          sudo -E -u postgres script/start_test_db.rb
-          sudo -u postgres psql -c "CREATE ROLE $PGUSER LOGIN SUPERUSER PASSWORD '$PGPASSWORD';"
-
-      - name: Container envs
-        id: container-envs
-        run: |
-          echo "ruby_version=$RUBY_VERSION" >> $GITHUB_OUTPUT
-          echo "debian_release=$DEBIAN_RELEASE" >> $GITHUB_OUTPUT
-        shell: bash
-
-      - name: Bundler cache
-        uses: actions/cache@v4
-        with:
-          path: vendor/bundle
-          key: >-
-            ${{ runner.os }}-
-            ${{ steps.container-envs.outputs.ruby_version }}-
-            ${{ steps.container-envs.outputs.debian_release }}-
-            ${{ hashFiles('**/Gemfile.lock') }}-
-            ${{ hashFiles('migrations/config/gemfiles/**/Gemfile') }}
-
-      - name: Setup gems
-        run: |
-          gem install bundler --conservative -v $(awk '/BUNDLED WITH/ { getline; gsub(/ /,""); print $0 }' Gemfile.lock)
-          bundle config --local path vendor/bundle
-          bundle config --local deployment true
-          bundle config --local without development
-          bundle install --jobs $(($(nproc) - 1))
-          # don't call `bundle clean` clean, we need the gems for the migrations
-
-      - name: Get yarn cache directory
-        id: yarn-cache-dir
-        run: echo "dir=$(yarn cache dir)" >> $GITHUB_OUTPUT
-
-      - name: Yarn cache
-        uses: actions/cache@v4
-        id: yarn-cache
-        with:
-          path: ${{ steps.yarn-cache-dir.outputs.dir }}
-          key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}
-
-      - name: Yarn install
-        run: yarn install --frozen-lockfile
-
-      - name: Fetch app state cache
-        uses: actions/cache@v4
-        id: app-cache
-        with:
-          path: tmp/app-cache
-          key: >-
-            ${{ runner.os }}-
-            ${{ hashFiles('.github/workflows/tests.yml') }}-
-            ${{ hashFiles('db/**/*', 'plugins/**/db/**/*') }}-
-            ${{ hashFiles('config/environments/test.rb') }}
-
-      - name: Restore database from cache
-        if: steps.app-cache.outputs.cache-hit == 'true'
-        run: script/silence_successful_output psql --quiet -o /dev/null -f tmp/app-cache/cache.sql postgres
-
-      - name: Restore uploads from cache
-        if: steps.app-cache.outputs.cache-hit == 'true'
-        run: rm -rf public/uploads && cp -r tmp/app-cache/uploads public/uploads
-
-      - name: Create and migrate database
-        if: steps.app-cache.outputs.cache-hit != 'true'
-        run: |
-          bin/rake db:create
-          script/silence_successful_output bin/rake db:migrate
-
-      - name: Dump database for cache
-        if: steps.app-cache.outputs.cache-hit != 'true'
-        run: mkdir -p tmp/app-cache && pg_dumpall > tmp/app-cache/cache.sql
-
-      - name: Dump uploads for cache
-        if: steps.app-cache.outputs.cache-hit != 'true'
-        run: rm -rf tmp/app-cache/uploads && cp -r public/uploads tmp/app-cache/uploads
-
-#      - name: Check core database drift
-#        run: |
-#          mkdir /tmp/intermediate_db
-#          ./migrations/scripts/schema_generator /tmp/intermediate_db/base_migration.sql
-#          diff -u migrations/common/intermediate_db_schema/000_base_schema.sql /tmp/intermediate_db/base_migration.sql
-
-      - name: RSpec
-        run: bin/rspec --default-path migrations/spec
-
-  runtime:
-    if: github.event_name == 'pull_request' || github.repository != 'discourse/discourse-private-mirror'
-    name: Runs on ${{ matrix.os }}, Ruby ${{ matrix.ruby }}
-    timeout-minutes: 20
-
-    strategy:
-      fail-fast: false
-
-      matrix:
-        os: ["ubuntu-latest", "macos-latest"]
-        ruby: ["3.2", "3.3"]
-
-    runs-on: ${{ matrix.os }}
-
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          fetch-depth: 1
-
-      - name: Modify path for libpq
-        if: matrix.os == 'macos-latest'
-        run: echo "/opt/homebrew/opt/libpq/bin" >> $GITHUB_PATH
-
-      - name: Setup Ruby
-        uses: ruby/setup-ruby@v1
-        with:
-          ruby-version: ${{ matrix.ruby }}
-          bundler-cache: true
-
-      - name: Run converter
-        working-directory: migrations
-        run: bin/convert version