Failing test: Aspire.Azure.Npgsql.Tests.ConformanceTests.BothDataSourceAndConnectionCanBeResolved

## Build Information
Build: https://dev.azure.com/dnceng-public/public/aspire/_build/results?buildId=1179534
Build error leg or test failing: Aspire.Azure.Npgsql.Tests.ConformanceTests.BothDataSourceAndConnectionCanBeResolved
Pull request:

## Error Message

Fill the error message using [step by step known issues guidance](https://github.com/dotnet/arcade/blob/main/Documentation/Projects/Build%20Analysis/KnownIssueJsonStepByStep.md).

```json
{
"ErrorMessage": "",
"ErrorPattern": "Docker.DotNet.DockerImageNotFoundException.*No such image: testcontainers/ryuk",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
```

## Error Details

```
Class fixture type 'Aspire.Azure.Npgsql.Tests.PostgreSQLContainerFixture' threw in InitializeAsync
---- Docker.DotNet.DockerImageNotFoundException : Docker API responded with status code=NotFound, response={"message":"No such image: testcontainers/ryuk:0.12.0"}
```

Stack Trace

```
----- Inner Stack Trace -----
at Docker.DotNet.ContainerOperations.<>c.<.cctor>b__30_1(HttpStatusCode statusCode, String responseBody) in /_/src/Docker.DotNet/Endpoints/ContainerOperations.cs:line 17
at Docker.DotNet.DockerClient.HandleIfErrorResponseAsync(HttpStatusCode statusCode, HttpResponseMessage response, IEnumerable`1 handlers) in /_/src/Docker.DotNet/DockerClient.cs:line 485
at Docker.DotNet.DockerClient.MakeRequestAsync[T](IEnumerable`1 errorHandlers, HttpMethod method, String path, IQueryString queryString, IRequestContent body, IDictionary`2 headers, TimeSpan timeout, CancellationToken token) in /_/src/Docker.DotNet/DockerClient.cs:line 246
at Docker.DotNet.ContainerOperations.CreateContainerAsync(CreateContainerParameters parameters, CancellationToken cancellationToken) in /_/src/Docker.DotNet/Endpoints/ContainerOperations.cs:line 54
at DotNet.Testcontainers.Clients.DockerContainerOperations.RunAsync(IContainerConfiguration configuration, CancellationToken ct) in /_/src/Testcontainers/Clients/DockerContainerOperations.cs:line 225
at DotNet.Testcontainers.Clients.TestcontainersClient.RunAsync(IContainerConfiguration configuration, CancellationToken ct) in /_/src/Testcontainers/Clients/TestcontainersClient.cs:line 339
at DotNet.Testcontainers.Containers.DockerContainer.UnsafeCreateAsync(CancellationToken ct) in /_/src/Testcontainers/Containers/DockerContainer.cs:line 493
at DotNet.Testcontainers.Containers.DockerContainer.StartAsync(CancellationToken ct) in /_/src/Testcontainers/Containers/DockerContainer.cs:line 337
at DotNet.Testcontainers.Containers.ResourceReaper.GetAndStartNewAsync(Guid sessionId, IDockerEndpointAuthenticationConfiguration dockerEndpointAuthConfig, IImage resourceReaperImage, IMount dockerSocket, ILogger logger, Boolean requiresPrivilegedMode, TimeSpan initTimeout, CancellationToken ct) in /_/src/Testcontainers/Containers/ResourceReaper.cs:line 224
at DotNet.Testcontainers.Containers.ResourceReaper.GetAndStartNewAsync(Guid sessionId, IDockerEndpointAuthenticationConfiguration dockerEndpointAuthConfig, IImage resourceReaperImage, IMount dockerSocket, ILogger logger, Boolean requiresPrivilegedMode, TimeSpan initTimeout, CancellationToken ct) in /_/src/Testcontainers/Containers/ResourceReaper.cs:line 248
at DotNet.Testcontainers.Containers.ResourceReaper.GetAndStartDefaultAsync(IDockerEndpointAuthenticationConfiguration dockerEndpointAuthConfig, ILogger logger, Boolean isWindowsEngineEnabled, CancellationToken ct) in /_/src/Testcontainers/Containers/ResourceReaper.cs:line 135
at DotNet.Testcontainers.Clients.TestcontainersClient.RunAsync(IContainerConfiguration configuration, CancellationToken ct) in /_/src/Testcontainers/Clients/TestcontainersClient.cs:line 319
at DotNet.Testcontainers.Containers.DockerContainer.UnsafeCreateAsync(CancellationToken ct) in /_/src/Testcontainers/Containers/DockerContainer.cs:line 493
at DotNet.Testcontainers.Containers.DockerContainer.StartAsync(CancellationToken ct) in /_/src/Testcontainers/Containers/DockerContainer.cs:line 337
at Aspire.Azure.Npgsql.Tests.PostgreSQLContainerFixture.InitializeAsync() in /_/tests/Aspire.Azure.Npgsql.Tests/PostgreSQLContainerFixture.cs:line 26
```

📊 **[View CI Failure Report](https://github.com/microsoft/aspire/issues/12389#issuecomment-4174837113)**

Start with tests/Aspire.Azure.Npgsql.Tests/PostgreSQLContainerFixture.cs at line 26 and the Aspire.Azure.Npgsql.Tests.ConformanceTests.BothDataSourceAndConnectionCanBeResolved test. Investigate the Testcontainers startup failure for testcontainers/ryuk:0.12.0, then rerun the failing test. Done means the fixture initializes and the conformance test passes without the missing-image error.

Written by the indexing model from the issue text.