Self-hosted Sentry can no longer integrate with Jira Cloud using the current installation flow

### Environment

self-hosted (https://develop.sentry.dev/self-hosted/)

### Steps to Reproduce

We are trying to integrate a self-hosted Sentry instance with Jira Cloud, but the current setup flow no longer works.

The self-hosted Jira integration appears to rely on the older Atlassian Connect private app installation approach. However, Atlassian has removed support for new Connect private app installations / descriptor updates for Jira Cloud, so this integration path is no longer usable for new setups.

As a result, we are unable to connect self-hosted Sentry to Jira Cloud in a supported way.

See https://developer.atlassian.com/platform/forge/changelog/#CHANGE-3096

### Expected Result

A supported method to integrate self-hosted Sentry with Jira Cloud, or updated documentation describing the replacement path.

### Actual Result

The available self-hosted integration path appears to depend on a deprecated/removed Atlassian installation model, so the integration cannot be installed for a new Jira Cloud environment.

### Product Area

Other

### Link

_No response_

### DSN

_No response_

### Version

_No response_

Start by reviewing the self-hosted Jira integration installation flow and the Atlassian Forge changelog linked in the issue. Determine the supported replacement for the removed Jira Cloud installation path, then document or implement that path and verify that a new self-hosted Sentry instance can connect to Jira Cloud.

Written by the indexing model from the issue text.