Fix duplicate plugin declaration warn in testsuite/preview/basic

[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.wildfly:wildfly-ts-preview-basic:jar:27.0.0.Alpha2-SNAPSHOT
[WARNING] 'profiles.profile[bootablejar.ee9.profile].plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.apache.maven.plugins:maven-resources-plugin @ line 595, column 29
[WARNING] 
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING] 
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
[WARNING]