chore: Send Slack runs on schedule or if `inputs.send_notification` is `true`

[oarbusi]

Description

Send Slack runs on schedule or if inputs.send_notification is true when the test result is failure

the job always runs on schedule and when triggered manually or called by another job it only runs if inputs.send_notification is checked. That's because:

• If the workflow is run on schedule, then inputs.should_run is null.
• The contains function converts its argument to a string: null is converted to ''.

Link to any related issue(s):

Type of change:

• [ ] Bug fix (non-breaking change which fixes an issue). Please, add the "bug" label to the PR.
• [ ] New feature (non-breaking change which adds functionality). Please, add the "enhancement" label to the PR. A migration guide must be created or updated if the new feature will go in a major version.
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected). Please, add the "breaking change" label to the PR. A migration guide must be created or updated.
• [ ] This change requires a documentation update
• [ ] Documentation fix/enhancement

Required Checklist:

• [ ] I have signed the MongoDB CLA
• [ ] I have read the contributing guides
• [ ] I have checked that this change does not generate any credentials and that they are NOT accidentally logged anywhere.
• [ ] I have added tests that prove my fix is effective or that my feature works per HashiCorp requirements
• [ ] I have added any necessary documentation (if appropriate)
• [ ] I have run make fmt and formatted my code
• [ ] If changes include deprecations or removals, I defined an isolated PR with a relevant title as it will be used in the auto-generated changelog.
• [ ] If changes include removal or addition of 3rd party GitHub actions, I updated our internal document. Reach out to the APIx Integration slack channel to get access to the internal document.

Further comments

[lantoli]

actionlint is failing:

84	if: ${{ !cancelled() && needs.tests.result == 'failure' && !contains(inputs.send_notification, 'false') }}	^~~~~~~~~ .github/workflows/test-suite.yml:84:74: 1st argument of function call is not assignable. "bool" cannot be assigned to "array". called function type is "contains(array, any) -> bool" [expression]
84	if: ${{ !cancelled() && needs.tests.result == 'failure' && !contains(inputs.send_notification, 'false') }}