Regression: `dotty/compile` should not compile bootstrapped projects

This is a regression after https://github.com/lampepfl/dotty/pull/3141, because asDottyRoot contains:
```scala
aggregate(`dotty-interfaces`, dottyLibrary, dottyCompiler, dottyDoc, `dotty-language-server`, dottySbtBridgeReference).
```

But `dotty-language-server` is a bootstrapped only project and should not be aggregated for the non-bootstrapped dotty root.