Don't install a shutdown hook by default operator-framework#434

Author: lburgazzoli

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/Operator.java

@@ -27,7 +27,9 @@ public Operator(KubernetesClient k8sClient, ConfigurationService configurationSe
     this.k8sClient = k8sClient;
     this.configurationService = configurationService;
     this.closeables = new ArrayList<>();
+  }
 
+  public void installShutdownHook() {
     Runtime.getRuntime().addShutdownHook(new Thread(this::close));
   }