[MPIR-445] Rendering content log junk during plugin's unit tests execution

**[Elliotte Rusty Harold](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=elharo)** opened **[MPIR-445](https://issues.apache.org/jira/browse/MPIR-445?redirect=false)** and commented

(Edit/clarification) When running `mvn test` of this plugin source code, unit tests have unwanted logs that hide Surefire results messages, like

```
[INFO] Running org.apache.maven.report.projectinfo.PluginManagementReportTest
[INFO] Rendering content with org.apache.maven.skins:maven-default-skin:jar:1.3 skin.
[INFO] Rendering content with org.apache.maven.skins:maven-default-skin:jar:1.3 skin.
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.662 s - in org.apache.maven.report.projectinfo.PluginManagementReportTest
```

Another log message that's unneeded and simply clutters the output:

[INFO] Rendering content with org.apache.maven.skins:maven-default-skin:jar:1.3 skin.

Reduce to debug or remove completely.

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No further details from [MPIR-445](https://issues.apache.org/jira/browse/MPIR-445?redirect=false)

Start by running `mvn test` and search the plugin source and tests for the message `Rendering content with org.apache.maven.skins:maven-default-skin:jar:1.3`, especially around `PluginManagementReportTest`. Trace where the rendering message is emitted, then verify with the test run that Surefire results are no longer obscured and the message is absent or only shown at debug level.

Written by the indexing model from the issue text.