Support linking the same slack workspace to a Sentry SaaS and Sentry Self hosted orgs

### Self-Hosted Version

24.6.0

### CPU Architecture

x86_64

### Docker Version

27.1.1

### Docker Compose Version

2.27.0

### Machine Specification

- [x] My system meets the minimum system requirements of Sentry

### Steps to Reproduce

1. Follow the instructions as outlined here


2. Run `/sentry link team` within slack
3. Follow the link to the following post
4. Only discover sentry.io projects here


### Expected Result

A way to discover/configure self hosted sentry instances on the last step.

### Actual Result

Only sentry.io hosted projects are discovered.

### Event ID

_No response_

Start with the Slack `/sentry link team` flow and trace how the final project or organization list is populated. Compare the available Sentry SaaS results with the self-hosted organization path; done means a user can discover and configure a self-hosted Sentry instance alongside a Sentry SaaS organization.

Written by the indexing model from the issue text.