Composite build from IDE does not always use included builds

If I have a structure like A -> B -> C, where each project is a separate build.

If I include all of these into a root build:
```
includeBuild 'A'
includeBuild 'B'
includeBuild 'C'
```
Gradle will build these all together when run from the root build, but Xcode will either be unable to build each of the projects or will only use external sources. Xcode does not build the same way as Gradle in this case.

If I include the other builds from A:
```
rootProject.name = 'A'
includeBuild 'B'
includeBuild 'C'
```
Then Xcode will use the included builds for B and C when building A, but will still use external dependencies or fail when building B individually.

Since Xcode always tries to run from the build containing the Xcode target, we will sometimes use the included builds, depending on where they are defined.

This also applies to source dependencies.

Reproduce the A → B → C structure with each project included from the root, then compare it with including B and C from A. Run the builds from each project’s Xcode target and observe whether included or external dependencies are selected; done means each project consistently uses the intended included or source dependencies.

Written by the indexing model from the issue text.