[Prod] Properly track eventSubmitted, updates to Slack message around PR deploys

[thewatermethod]

Description of change

We need to capture the "eventSubmitted" variable in the data of a Training Report when the owner submits it. The "complete event" functionality depends on it. It seems to have been removed as part of a bug squash in the days leading up to the TR release.

This PR also includes code to further customize the slack message deployments.

How to test

Impersonating the user in this slack thread, confirm that you can submit and then complete the event in question

Alternately, confirm "eventSubmitted" is present in the request body when submitting a training report. A unit test has been added to validate this specific field.

Issue(s)

• https://jira.acf.gov/browse/TTAHUB-3336

Checklists

Every PR

• Meets issue criteria
• JIRA ticket status updated
• Code is meaningfully tested
• Meets accessibility standards (WCAG 2.1 Levels A, AA)
• API Documentation updated
• Boundary diagram updated
• Logical Data Model updated
• Architectural Decision Records written for major infrastructure decisions
• UI review complete

Before merge to main

• OHS demo complete
• Ready to create production PR

Production Deploy

• Staging smoke test completed

After merge/deploy

• Update JIRA ticket status

[kryswisnaskas]

Merging since this PR is time sensitive.