[release/9.4] Throw if container runtime is unhealthy during image build

[github-actions]

Backport of #10399 to release/9.4

/cc @captainsafia

Customer Impact

• The fix adds a health check at the start of ResourceContainerImageBuilder.BuildImagesAsync. If the runtime isn’t running, we now log an error and throw InvalidOperationException with a clear message, immediately failing the publish step

Testing

• Unit tests added in ResourceContainerImageBuilderTests
• Manual validation: stopped Docker daemon and confirmed the new exception and log entry appear and that publish

Risk

Low. The change is isolated to the image-building path and is only triggered when the container runtime is unhealthy.

Regression?

No.

[captainsafia]

@dotnet/aspire-push Can I get help merging this?