Use port 8800 for Cosmos emulator on Helix

[AndriySvyryd]

Don't skip tests if emulator not available

Fixes #19973

[AndriySvyryd]

Depends on https://dev.azure.com/dnceng/internal/_git/dotnet-helix-machines/pullrequest/54999?_a=overview

[AndriySvyryd]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Copilot]

Pull request overview

This PR configures the Cosmos DB emulator to use port 8800 specifically for Helix CI runs and adds a mechanism to skip connection checks to prevent tests from being skipped when the emulator is not immediately available.

Changes:

• Adds a SkipConnectionCheck configuration flag that bypasses connection availability checks
• Configures Helix Windows builds to use port 8800 for the Cosmos emulator and skip connection checks
• Simplifies the GitHub Actions Cosmos test workflow by combining restore, build, and test into a single command

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
test/EFCore.Cosmos.FunctionalTests/TestUtilities/TestEnvironment.cs	Adds SkipConnectionCheck property to read configuration for bypassing connection checks
test/EFCore.Cosmos.FunctionalTests/TestUtilities/CosmosTestStore.cs	Updates IsConnectionAvailableAsync to return true immediately when SkipConnectionCheck is enabled
eng/helix.proj	Adds Cosmos test configuration for Windows Helix queues with port 8800 and connection check skip
.github/workflows/TestCosmos.yaml	Simplifies workflow by combining build and test steps, adds SkipConnectionCheck environment variable

[AndriySvyryd]

The tests are now failing with

       Microsoft.EntityFrameworkCore.Storage.RetryLimitExceededException : The maximum number of retries (10) was exceeded while executing database operations with 'TestCosmosExecutionStrategy'. See the inner exception for the most recent failure.
      ---- Microsoft.Azure.Cosmos.CosmosException : Response status code does not indicate success: ServiceUnavailable (503); Substatus: 20003; ActivityId: ad961a25-4cb0-4a83-b8ab-21017b93f97e; Reason: (GatewayStoreClient Request Timeout. Start Time UTC:1/12/2026 10:43:24 PM; Total Duration:36003.5648 Ms; Request Timeout 20000 Ms; Http Client Timeout:1200000 Ms; Activity id: ad961a25-4cb0-4a83-b8ab-21017b93f97e;);; Diagnostics:{"Summary":{},"name":"Account Read","start datetime":"2026-01-12T22:43:24.301Z","duration in milliseconds":36002.4951}
      --------- System.Threading.Tasks.TaskCanceledException : The operation was canceled.
      ------------ System.Threading.Tasks.TaskCanceledException : The operation was canceled.
      ---------------- System.IO.IOException : Unable to read data from the transport connection: The I/O operation has been aborted because of either a thread exit or an application request..
      -------------------- System.Net.Sockets.SocketException : The I/O operation has been aborted because of either a thread exit or an application request.