Feature Request: Native support for Jira Cascading Select custom fields in Sentry Jira Integration

### Problem Statement

Context:
Our organization relies heavily on the Sentry-Jira integration to streamline our incident management and bug tracking workflows, allowing developers to quickly create Jira issues directly from Sentry errors.

The Problem:
The current Sentry Jira integration does not natively support the Jira "Cascading Select" custom field type. Instead of rendering the linked parent and child dropdown menus required by this field type, Sentry's UI currently renders these fields incorrectly (often as a simple, flat text input box), or fails to load them at all.

Workflow Impact:
We utilize several mandatory cascading select fields on our Jira "Create Issue" screens to handle critical internal ticket routing. Because these fields are required, the integration cannot successfully submit the "Create Issue" payload to the Jira API.

This limitation results in a complete workflow blocker, preventing our teams from using Sentry's native Jira ticket creation feature. We are unable to use suggested workarounds (such as making the fields optional, altering our internal Jira configuration, or using external automation) as doing so would compromise our established organization-wide routing and reporting structures.

We have confirmed with Sentry support that no built-in workaround for this limitation exists, and we were directed to raise this new feature request so it can be surfaced to the Product team. As noted by the Sentry support team: "We don't have a built in workaround for now, go ahead and file a feature request using this link and we will surface that to our EPD team."

### Solution Brainstorm

Solution Brainstorm
Update the Sentry Jira Integration to natively detect and support Jira "Cascading Select" custom field types.

Implement UI support in the Sentry "Create Jira Issue" modal to render these fields as two linked dropdown menus (Parent and Child), mimicking native Jira functionality.

Ensure the backend payload correctly maps and sends both the selected parent and child values to the Jira API upon issue submission.

### Product Area

Issues

Start with the Sentry Create Jira Issue modal and the Jira API payload handling. Confirm how Jira Cascading Select fields are represented, then verify that parent and child selections render and submit correctly; done means mandatory cascading fields can be used to create a Jira issue.

Written by the indexing model from the issue text.