remove indy changes for grails

Author: SylvainJuge

instrumentation/grails-3.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/grails/GrailsInstrumentationModule.java

@@ -10,21 +10,14 @@
 import com.google.auto.service.AutoService;
 import io.opentelemetry.javaagent.extension.instrumentation.InstrumentationModule;
 import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
-import io.opentelemetry.javaagent.extension.instrumentation.internal.ExperimentalInstrumentationModule;
 import java.util.List;
 
 @AutoService(InstrumentationModule.class)
-public class GrailsInstrumentationModule extends InstrumentationModule
-    implements ExperimentalInstrumentationModule {
+public class GrailsInstrumentationModule extends InstrumentationModule {
   public GrailsInstrumentationModule() {
     super("grails", "grails-3.0");
   }
 
-  @Override
-  public String getModuleGroup() {
-    return "servlet";
-  }
-
   @Override
   public List<TypeInstrumentation> typeInstrumentations() {
     return asList(