Add a nightly/weekly e2e test run

[yitsushi]

Right now we have an e2e test, but we don't maintain and use it. When we change our code the e2e test is usually left out, as a result it needs some love before we can use it (see #172).

Acceptance Criteria:

• There is a GitHub action to run e2e test.
• The action can be triggered manually.
• The action runs periodically (daily, weekly N times [N > 0]) and reports error to the #team-sunglow channel (both success and failed).