[CI] Remove Slack bot from CI failure monitor (#21581)

Co-authored-by: Alison Shao <alison.shao@Mac.attlocal.net>

.github/workflows/ci-failure-monitor.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install requests slack_sdk
+          pip install requests
 
       - name: Run Failure Analysis
         env:
@@ -51,22 +51,3 @@ jobs:
           path: |
             scripts/ci_monitor/ci_failure_analysis_*.json
           retention-days: 7
-
-      - name: Send Slack Notification
-        if: always()
-        env:
-          SGLANG_DIFFUSION_SLACK_TOKEN: ${{ secrets.SGLANG_DIFFUSION_SLACK_TOKEN }}
-        run: |
-          cd scripts/ci_monitor
-          LATEST_REPORT=$(ls -t ci_failure_analysis_*.json | head -1)
-
-          if [ ! -f "$LATEST_REPORT" ]; then
-            echo "No report found, so skipping Slack notification"
-            exit 0
-          fi
-
-          if [ -n "$SGLANG_DIFFUSION_SLACK_TOKEN" ]; then
-            python3 post_ci_failures_to_slack.py --report-file "$LATEST_REPORT"
-          else
-            echo "SGLANG_DIFFUSION_SLACK_TOKEN not configured, skipping notification"
-          fi