C# compiler does not detect missing await in an async lambda which calls async func.

**Version Used**:
Net10.0, Net9.0

**Steps to Reproduce**:
See repro following:

[https://github.com/Jurgen-Fischer/Bug_CSharp_missing_await_not_detected_inside_async_lambda](url)

**Diagnostic Id**:
n/a

**Expected Behavior**:
Detect missing await in an async lambda which calls async func.

**Actual Behavior**:
Does not detect missing await in an async lambda which calls async func.

Start with the linked Bug_CSharp_missing_await_not_detected_inside_async_lambda reproduction and compare the compiler's behavior on the reported async lambda in .NET 9.0 and .NET 10.0. Trace the relevant C# compiler diagnostic path and add coverage for the case; done means the missing await is detected as expected.

Written by the indexing model from the issue text.