Tests the test-upgrade scripts themselves (#10664)

## Problem
We run the compatibility tests only if we are upgrading the extension.
An accidental code change may break the test itself, so we have to check
this code as well.
## Summary of changes
The test is scheduled once a day to save time and resources.

---------

Co-authored-by: Alexander Bayandin <alexander@neon.tech>

.github/workflows/force-test-extensions-upgrade.yml

@@ -0,0 +1,76 @@
+name: Force Test Upgrading of Extension
+on:
+  schedule:
+    # * is a special character in YAML so you have to quote this string
+    #          ┌───────────── minute (0 - 59)
+    #          │ ┌───────────── hour (0 - 23)
+    #          │ │ ┌───────────── day of the month (1 - 31)
+    #          │ │ │ ┌───────────── month (1 - 12 or JAN-DEC)
+    #          │ │ │ │ ┌───────────── day of the week (0 - 6 or SUN-SAT)
+    - cron:  '45 2 * * *' # run once a day, timezone is utc
+  workflow_dispatch: # adds ability to run this manually
+
+defaults:
+  run:
+    shell: bash -euxo pipefail {0}
+
+concurrency:
+  # Allow only one workflow
+  group: ${{ github.workflow }}
+  cancel-in-progress: true
+
+permissions:
+  id-token: write # aws-actions/configure-aws-credentials
+  statuses: write
+  contents: read
+
+jobs:
+  regress:
+    strategy:
+      fail-fast: false
+      matrix:
+        pg-version: [16, 17]
+
+    runs-on: small
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: false
+
+      - name: Get the last compute release tag
+        id: get-last-compute-release-tag
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          tag=$(gh api -q '[.[].tag_name | select(startswith("release-compute"))][0]'\
+            -H "Accept: application/vnd.github+json" \
+            -H "X-GitHub-Api-Version: 2022-11-28" \
+            "/repos/${GITHUB_REPOSITORY}/releases")
+          echo tag=${tag} >> ${GITHUB_OUTPUT}
+
+      - name: Test extension upgrade
+        timeout-minutes: 20
+        env:
+          NEWTAG: latest
+          OLDTAG: ${{ steps.get-last-compute-release-tag.outputs.tag }}
+          PG_VERSION: ${{ matrix.pg-version }}
+          FORCE_ALL_UPGRADE_TESTS: true
+        run: ./docker-compose/test_extensions_upgrade.sh
+
+      - name: Print logs and clean up
+        if: always()
+        run: |
+          docker compose --profile test-extensions -f ./docker-compose/docker-compose.yml logs || true
+          docker compose --profile test-extensions -f ./docker-compose/docker-compose.yml down
+
+      - name: Post to the Slack channel
+        if: ${{ github.event.schedule && failure() }}
+        uses: slackapi/slack-github-action@v1
+        with:
+          channel-id: ${{ vars.SLACK_ON_CALL_QA_STAGING_STREAM }}
+          slack-message: |
+            Test upgrading of extensions: ${{ job.status }}
+            <${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}|GitHub Run>
+        env:
+          SLACK_BOT_TOKEN: ${{ secrets.SLACK_BOT_TOKEN }}