fix: remove groovy plugin from grails-layout

The groovy plugin gets applied by `grails-plugin`.

Author: matrei

grails-gsp/grails-layout/build.gradle

@@ -17,7 +17,6 @@
  *  under the License.
  */
 plugins {
-    id 'groovy'
     id 'java-library'
     id 'project-report'
     id 'org.apache.grails.buildsrc.properties'