Graphs aren't generated when running the multi-rule task, even when they're enabled

With this config:
```kotlin
moduleCheck {
  reports {
    graphs {
      enabled = true // default is false
    }
  }
}
```
expected: Running `./gradlew modulecheckauto` should generate graph reports in the build directory of each module.  
actual: nothing is generated

Running `./gradlew modulecheckgraphs` does generate the graphs.