Remove Slack notification on failed link check

We're going to use a Bennett Bot regular reminder and display the
existing workflow status in the tech support Slack channel.

The token is used elsewhere in other repositories, so we don't need to
remove this from secrets just yet.

.github/workflows/check_links.yml

@@ -46,13 +46,3 @@ jobs:
           fail: true
         env:
           GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
-
-      - name: "Notify Slack on Failure"
-        if: ${{ failure() && github.event_name == 'schedule' }}
-        uses: zuplo/github-action-slack-notify-build@cf8e7e66a21d76a8125ea9648979c30920195552 # v2
-        env:
-          SLACK_BOT_TOKEN: ${{ secrets.SLACK_BOT_TOKEN }}
-        with:
-          channel_id: C0270Q313H7
-          status: "Check Docs Links Failure"
-          color: danger