Remove downstream checks, which is just noise (#985)

Author: Carreau

.github/workflows/downstream.yml

@@ -58,18 +58,3 @@ jobs:
         with:
           package_name: notebook
           test_command: pytest -vv --ignore-glob=notebook/tests/selenium/* --ignore-glob=notebook/nbconvert/tests/* --ignore-glob=notebook/services/nbconvert/tests/*
-
-  downstream_check: # This job does nothing and is only used for the branch protection
-    if: always()
-    needs:
-      - notebook
-      - ipywidgets
-      - jupyter_server
-      - nbconvert
-      - ipython
-    runs-on: ubuntu-latest
-    steps:
-      - name: Decide whether the needed jobs succeeded or failed
-        uses: re-actors/alls-green@release/v1
-        with:
-          jobs: ${{ toJSON(needs) }}