Cron issues not triggering issue webhooks

### Environment

SaaS (https://sentry.io/)

### Steps to Reproduce

1. Create an internal integration
2. Add a webhook endpoint
3. Enable "Issue" webhook for "created, resolved, assigned, archived, unresolved"
4. Create a cron monitor alert
5. Trigger a failure in the cron monitor

### Expected Result

Sentry sends a "Issue created" webhook request to the defined in the internal integration.

The webhook documentation does not mention limitations on which kind of issues can trigger webhooks, thus it is expected that all issues can trigger webhooks.

### Actual Result

No webhook is sent.

Scenarios where no webhook request is sent:
1. Cron monitor issue creation
2. Cron monitor issue auto-resolve by new OK check-in

Scenarios where a webhook request is sent:
1. Cron monitor issue automatically assigned
2. Cron monitor issue manually resolved

### Product Area

Settings - Integrations

### Link

_No response_

### DSN

_No response_

### Version

_No response_

The issue names no source files, tests, or entry points; begin by reproducing the internal-integration flow for cron monitor issue creation and auto-resolution. Trace the Issue webhook dispatch path and existing coverage; done means both events send the expected webhook while assignment and manual resolution continue to work.

Written by the indexing model from the issue text.