ServiceDescriptor and IServiceCollection missing instance and factory registration overloads

Reproduction A steps (Runtime behavior - two instances created):

1. Open the attached “IN-143711“ project
2. Open the “Assets/Scenes/SampleScene.unity” Scene
3. Enter Play mode
4. Observe the Console

Actual result: An error is logged (“BUG REPRODUCED: the two interfaces resolved to DIFFERENT FooService instances”)
Expected result: This error is not logged

Reproduction B steps (Compile error)

1. Open the attached “IN-143711” project
2. Open the “Assets/Repro/Scripts/ReproAppBuilder.cs“ script
3. Uncomment lines 54 and 55
4. Save the file and let Unity recompile
5. Observe the Console

Actual result: An error is logged (“The non-generic method 'ServiceDescriptor.Singleton(Type, Type)' cannot be used with type arguments“)
Expected result: The project compiles and no errors are logged

Reproducible with: 2.1.7 (6000.5.0b11)2.1.11 (6000.0.75f1, 6000.3.17f1, 6000.4.10f1), 2.2.0-pre.11 (6000.5.0b11)

Reproducible on: macOS 26.5.1
Not reproducible on: No other environments tested