TST: Remove custom action-ci-skip

like astropy/astropy#11316

.github/workflows/ci_workflows.yml

@@ -13,28 +13,11 @@ on:
       - master
 
 jobs:
-  cancel_ci:
-    name: Mandatory checks before CI
-    runs-on: ubuntu-latest
-    outputs:
-      run_next: ${{ steps.skip_ci_step.outputs.run_next }}
-    steps:
-    - name: Check skip CI
-      uses: OpenAstronomy/action-skip-ci@main
-      id: skip_ci_step
-      with:
-        NO_FAIL: true
-        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-
-  # The rest only run if above are done
-
   # Github Actions supports ubuntu, windows, and macos virtual environments:
   # https://help.github.com/en/actions/reference/virtual-environments-for-github-hosted-runners
   ci_tests:
     name: ${{ matrix.name }}
     runs-on: ${{ matrix.os }}
-    needs: cancel_ci
-    if: needs.cancel_ci.outputs.run_next == 'true'
     strategy:
       matrix:
         include: