StrawberryShake subscription returns before ready - timing issue

Is there an existing issue for this?

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Describe the bug

Context:
Topic: Automated API/integration tests.
Project: dotgraphee
Issue: StrawberryShake's subscription .Watch().Subscribe() seem to return before the system is ready to receive subscriptions.
(Cleanup: .Subscribe() returns an IDisposable which is disposed by the test fixture TearDown. We didn't forget it. 😉 )
Workaround: Thread.Sleep(1000); after subscription is started. 😢

Steps to reproduce

1. Set up a HotChocolate endpoint with subscriptions.
2. Set up a StrawberryShake client to subscribe and trigger that subscription with a mutation.
3. Create a test that calls the mutation immediately after starting the subscription, see image above. (dotgraphee is building a branch 'feature/strawberry-shake-client' that does step 1, 2 and 3.)
4. Test may pass randomly or when run in isolation. Create several or run in loop to reproduce.

Relevant log output

No response

Additional Context?

No response

Product

Strawberry Shake

Version

12.6.2

Start with the StrawberryShake subscription .Watch().Subscribe() path and the automated integration-test setup described in the issue. Reproduce the HotChocolate endpoint and client sequence with the mutation immediately after subscription, then verify repeated runs receive the subscription without Thread.Sleep(1000).