[MNG-8695] Too Many DefaultProjectBulder classes

**[Elliotte Rusty Harold](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=elharo)** opened **[MNG-8695](https://issues.apache.org/jira/browse/MNG-8695?redirect=false)** and commented

There exist both org.apache.maven.internal.impl.DefaultProjectBuilder and org.apache.maven.project.DefaultProjectBuilder and this has caused me confusion and problems when working on the code. We can probably combine these classes, but if not one of them should be renamed. E.g. org.apache.maven.internal.impl.DefaultProjectBuilder --> org.apache.maven.internal.impl.ImplProjectBuilder

---
No further details from [MNG-8695](https://issues.apache.org/jira/browse/MNG-8695?redirect=false)

Start by inspecting org.apache.maven.internal.impl.DefaultProjectBuilder and org.apache.maven.project.DefaultProjectBuilder to compare their responsibilities and usages. Determine whether they can be combined or whether one should be renamed, then verify that the resulting names no longer cause ambiguity across the Maven codebase.

Written by the indexing model from the issue text.