[MNG-8227] Cleanup after Sisu upgrade

**[Konrad Windszus](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=kwin)** opened **[MNG-8227](https://issues.apache.org/jira/browse/MNG-8227?redirect=false)** and commented

After the upgrade to Sisu 0.9.0 in MNG-7913 some code is no longer necessary:

[PathConverter](https://github.com/apache/maven/blob/acec540547bca289b0579ab0c8f371004b8903f1/maven-core/src/main/java/org/apache/maven/configuration/internal/DefaultBeanConfigurator.java#L175) (shipped with https://github.com/eclipse-sisu/sisu.plexus/commit/8800f2d47ac15e4e059a9dc3bd59e6a39abad49b)

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**Issue Links:**
- [MNG-7913](https://issues.apache.org/jira/browse/MNG-7913) Upgrade Sisu version to 0.9.0.M2
(_**"is caused by"**_)

Start with maven-core/src/main/java/org/apache/maven/configuration/internal/DefaultBeanConfigurator.java at the PathConverter reference, then read MNG-7913 to understand the Sisu 0.9.0 upgrade. Confirm which code became unnecessary after that upgrade and verify the Maven core build after cleanup.

Written by the indexing model from the issue text.