ci: remove ci-failure

bors-ng now consider skipped job as fail.

.github/workflows/ci.yml

@@ -128,7 +128,7 @@ jobs:
       - uses: actions/checkout@v2
       - run: shellcheck **/*.sh
 
-  # These jobs don't actually test anything, but they're used to tell bors the
+  # This job doesn't actually test anything, but they're used to tell bors the
   # build completed, as there is no practical way to detect when a workflow is
   # successful listening to webhooks only.
   #
@@ -150,19 +150,3 @@ jobs:
     steps:
       - name: Mark the job as a success
         run: exit 0
-  ci-failure:
-    name: ci
-    if: github.event_name == 'push' && !success()
-    needs:
-      - test
-      - build
-      - expandtest
-      - miri
-      - clippy
-      - rustfmt
-      - rustdoc
-      - shellcheck
-    runs-on: ubuntu-latest
-    steps:
-      - name: Mark the job as a failure
-        run: exit 1