fix: Quarkus doesn't like anonymous interface implementations

Author: metacosm

api/src/main/java/io/javaoperatorsdk/operator/api/config/DefaultRetryConfiguration.java

@@ -0,0 +1,4 @@
+package io.javaoperatorsdk.operator.api.config;
+
+public class DefaultRetryConfiguration implements RetryConfiguration {
+}

api/src/main/java/io/javaoperatorsdk/operator/api/config/RetryConfiguration.java

@@ -1,8 +1,7 @@
 package io.javaoperatorsdk.operator.api.config;
 
 public interface RetryConfiguration {
-    RetryConfiguration DEFAULT = new RetryConfiguration() {
-    };
+    RetryConfiguration DEFAULT = new DefaultRetryConfiguration();
 
     int DEFAULT_MAX_ATTEMPTS = 5;
     long DEFAULT_INITIAL_INTERVAL = 2000L;