Speeding up maven clean
The following advice appears to be for maven 1.x.
How can a 'qclean' profile as described above (or equivalent) be defined in maven 3.x settings.xml ?
The build element can only be specified in a profile of your project, not globally in the settings.xml. This is explained in the maven settings reference:
The profile element in the settings.xml is a truncated version of the pom.xml profile element. It consists of the activation, repositories, pluginRepositories and properties elements.
The profile elements only include these four elements because they concerns themselves with the build system as a whole (which is the role of the settings.xml file), not about individual project object model settings.
The linked article does not mention the settings.xml or maven 1 as far as I can see. As the article is from 2009 I guess the workaround was implemented for maven 2 and included in the projects pom.