Implement the specified notification system for test suite failures on Jenkins

This is what follow from #10296 (closed) once we deem it’s time to go ahead.

Blueprint: https://tails.boum.org/blueprint/automated_builds_and_tests/automated_tests_specs/

Parent Task: #5288 (closed)

Related issues

• Blocked by #10296 (closed)

Original created by @intrigeri on 10382 (Redmine)