Add Support for "Cascading" Custom Field Type for Jira Integration

### Problem Statement

Currently only custom field types that are supported for Jira integration is "single-select"

Related to internal ticket [#161897]()

### Solution Brainstorm

Add support for "cascading" custom field type to Jira integration

### Product Area

Settings - Integrations

We want to define a set of [lightweight metrics]() that SDKs can automatically collect for e.g. framework, language or platform, focusing only on signals that **do NOT overlap with Tracing**. Ideally these metrics should give a quick sense of app or runtime health, … while deeper investigation will still rely on traces or profiles.

Examples**:**

* Node.js runtime metrics (e.g., event loop delay, heap usage)
* Prisma-related metrics in Next.js
* Mobile CPU / memory usage to help surface potential ANRs or app hangs

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**Candidate Metrics (add more below)**

* …

*(please also add ideas, questions or examples in comments)*

Start in Settings - Integrations and trace the existing Jira integration support for the single-select custom field type. Review the related internal ticket and comment discussion to establish the expected cascading-field behavior; the work is complete when cascading custom fields are supported by the Jira integration and the relevant behavior is covered by tests.

Written by the indexing model from the issue text.