[CI Failure] Flaky: DockerComposeTests.DeployWithDashboard_PrintsDashboardAndServiceEndpoints fails due to port already in use

## Build Information

Build: https://github.com/microsoft/aspire/actions/runs/29060081150
Build error leg or test failing: Tests / Hosting.Docker / Hosting.Docker (ubuntu-latest) / `Aspire.Hosting.Docker.Tests.DockerComposeTests.DeployWithDashboard_PrintsDashboardAndServiceEndpoints`
Pull request: #18698

## Error Message

```
Error response from daemon: failed to set up container networking: driver failed programming external connectivity on endpoint aspire-env-c0bc8a71-nginx-1: failed to bind host port for 0.0.0.0:54398:172.18.0.2:80/tcp: address already in use
'docker compose up' failed with exit code 1.
Assert.Contains() Failure: Filter not matched in collection
Collection: []
```

## Description

Flaky: DockerComposeTests.DeployWithDashboard_PrintsDashboardAndServiceEndpoints fails due to port already in use

**Type**: flaky-test

## Occurrences

| Date | Build | Job | PR |
|------|-------|-----|----|
| 2026-07-10 | [29060081150](https://github.com/microsoft/aspire/actions/runs/29060081150) | Tests / Hosting.Docker / Hosting.Docker (ubuntu-latest) | #18698 |
| 2026-07-13 | [29220139824](https://github.com/microsoft/aspire/actions/runs/29220139824) | Tests / Hosting.Docker / Hosting.Docker (ubuntu-latest) | #18738 |
| 2026-08-04 | [30869057632](https://github.com/microsoft/aspire/actions/runs/30869057632) | Tests / Hosting.Docker / Hosting.Docker (ubuntu-latest) | #18930 |
| 2026-09-15 | [35023788042](https://github.com/microsoft/aspire/actions/runs/35023788042) | Tests / No-package tests (regular, Aspire.Hosting.Docker.Tests, Hosting.Docker, Hosting.Docker, tests/Asp... / Hosting.Docker (ubuntu-latest) | #20052 |

Start with Aspire.Hosting.Docker.Tests.DockerComposeTests.DeployWithDashboard_PrintsDashboardAndServiceEndpoints and reproduce it in the Hosting.Docker test job. Investigate how the test obtains host port 54398 and how Docker Compose cleanup is handled; done means repeated runs no longer fail with an address-already-in-use error.

Written by the indexing model from the issue text.