chore: Run monitor API test at 9am every day

[lym953]

What does this PR do?

There's a GitHub action testing if Serverless Plugin can fetch the recommended monitors properly from monitor API. Right now it runs on push and pull_request. This PR makes it also run at 9am EDT every day, and notify serverless-onboarding-and-enablement-ops channel if the test fails.

Motivation

Testing Guidelines

Test in prod

Additional Notes

Types of changes

• [ ] Bug fix
• [ ] New feature
• [ ] Breaking change
• [x] Misc (docs, refactoring, dependency upgrade, etc.)

Check all that apply

• [x] This PR's description is comprehensive
• [ ] This PR contains breaking changes that are documented in the description
• [ ] This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• [ ] This PR impacts documentation, and it has been updated (or a ticket has been logged)
• [ ] This PR's changes are covered by the automated tests
• [ ] This PR collects user input/sensitive content into Datadog

[lym953]

/merge

[dd-devflow[bot]]

:steam_locomotive: MergeQueue: pull request added to the queue

The median merge time in main is 2m.

Use /merge -c to cancel this operation!

[lym953]

Yay, the test ran every day for the past 3 days.