Add test result to slack automatically when daily or merged tests failed

[3r1ccc]

Signed-off-by: Eric Chang ericcc@infuseai.io

PR checklist

• [X] Ensure you have added or ran the appropriate tests for your PR.
• [X] DCO signed

What type of PR is this? Feature

What this PR does / why we need it: Current message is not that visible, add an image to alert

Which issue(s) this PR fixes: Add image to slack message Change to #dev

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE