ci: remove unused test-actions workflow

.github/workflows/test-actions.yml

@@ -1,41 +0,0 @@
-name: Test actions
-
-# Intended to only be run manually for testing actions in isolation.
-on:
-  workflow_dispatch:
-
-jobs:
-  test-summary:
-    runs-on: ubuntu-latest
-    name: Test summary (${{ matrix.message.name }})
-
-    strategy:
-      matrix:
-        message:
-          - name: success
-            text: "|Success|✅|✅|"
-            expect: ""
-          - name: failure
-            text: "|Failure|❌|❌|"
-            expect: "❌🔬 Tests failed: 2"
-
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-
-      - name: Generate
-        shell: bash
-        run: |
-          echo "${{ matrix.message.text }}" > test-result.md
-
-      - name: Upload
-        uses: actions/upload-artifact@v4
-        with:
-          path: test-result.md
-          name: test-result-${{ matrix.message.name }}
-
-      - name: Test
-        uses: ./.github/actions/test-summary
-        with:
-          download-pattern: test-result-${{ matrix.message.name }}
-          upload-name: summary-${{ matrix.message.name }}