CTS: Report error when CTS fails (#4219)

The CTS nightly stops report error because of `continue-on-error` is set
to true. Remove that field such that it will fail the job.

Add slack notification about the CTS status, this will report the status
of CTS nightly result to our slack dev channel.

.github/workflows/vk-gl-cts-nightly.yml

@@ -12,7 +12,6 @@ jobs:
   build:
     runs-on: [Windows, self-hosted]
     timeout-minutes: 180
-    continue-on-error: true
     steps:
     - uses: actions/checkout@v4
       with:
@@ -54,3 +53,14 @@ jobs:
       working-directory: ${{ github.workspace }}\VK-GL-CTS_WithSlang-0.0.3-win64\VK-GL-CTS_WithSlang-0.0.3-win64
       run: |
         .\deqp-vk.exe --deqp-archive-dir=${{ github.workspace }}\VK-GL-CTS_WithSlang-0.0.3-win64\VK-GL-CTS_WithSlang-0.0.3-win64 --deqp-caselist-file=${{ github.workspace }}\VK-GL-CTS_WithSlang-0.0.3-win64\VK-GL-CTS_WithSlang-0.0.3-win64\slang-passing-tests.txt
+    - name: result notification
+      id: slack-notify
+      if : always()
+      uses: slackapi/slack-github-action@v1.26.0
+      with:
+        payload: |
+          {
+            "CTS-Nightly": "CTS nightly status: ${{ job.status }}: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}"
+          }
+      env:
+        SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}