kie-wb-webapp: non need to skip tests as there are none
kie-wb-webapp: refactor gwt-maven-plugin config to avoid duplication

 * list of common GWT source artifacts is shared between product
   and community builds. Specifci Home Page artifacts are added
   by particular profiles.

 * the config change should not impact how the WAR is actually
   being built. Following will still work: "mvn clean install",
   "mvn clean install -Dfull", "mvn clean install -Dproducized"
   and "mvn clean install -Dproductized -Dfull".
Fix formatting