HBX-3096: Add execution to 'exec-maven-plugin' to perform clean for the Gradle plugin subproject

  - Restore the 'maven.repo.local' system property when invoking 'gradle clean build' to ${settings.localRepository}

Signed-off-by: Koen Aers <[email protected]>

Author: koentsje

gradle/pom.xml

@@ -76,6 +76,7 @@
                               <argument>build</argument>
                               <argument>-PprojectVersion=${project.version}</argument>
                               <argument>-Ph2Version=${h2.version}</argument>
+                              <argument>-Dmaven.repo.local=${settings.localRepository}</argument>
                           </arguments>
                       </configuration>
                       <goals>