Invalid project_id returned in error.created webhook

### Environment

SaaS (https://sentry.io/)

### Steps to Reproduce

1. Configure internal-integration webhook on error.created
2. Send error to sentry and inspect what was received on webhook. (project_id is incorrect)

See https://www.notion.so/sentry/Invalid-project_id-returned-in-error-created-webhook-6b7e3aaa487f4966855bf817ef309066 for full info

### Expected Result

project_id should be correct/as-expected

### Actual Result

project_id is not expected value, it's a project that isn't even valid

### Product Area

Settings - Developer Settings

### Link

_No response_

### DSN

_No response_

### Version

_No response_

Start by reproducing the internal-integration webhook for error.created and compare its project_id with the expected project. The issue names no files, tests, or entry points; use the linked Notion report for the missing details. Done means the webhook returns the correct project_id for the reproduced case.

Written by the indexing model from the issue text.