Fix code smells; remove unnecessary cleanup config in Concierge.

Signed-off-by: Yufei Cai <yufei.cai@bosch.io>

base/model/src/main/java/org/eclipse/ditto/base/model/common/HttpStatus.java

@@ -407,7 +407,7 @@ public final class HttpStatus {
     public static final HttpStatus NETWORK_CONNECT_TIMEOUT = assign(599);
 
     private final int code;
-    private final transient Category category;
+    private final Category category;
 
     private HttpStatus(final int code, final Category category) {
         this.code = code;

base/model/src/main/java/org/eclipse/ditto/base/model/exceptions/DittoRuntimeException.java

@@ -48,10 +48,8 @@ public abstract class DittoRuntimeException extends RuntimeException
         implements Jsonifiable.WithPredicate<JsonObject, JsonField>, DittoHeadersSettable<DittoRuntimeException>,
         WithManifest {
 
-    private static final long serialVersionUID = -7010323324132561106L;
-
     private final String errorCode;
-    private final HttpStatus httpStatus;
+    private final transient HttpStatus httpStatus;
     private final String description;
     private final URI href;
     private final transient DittoHeaders dittoHeaders; // not serializable!

concierge/service/src/main/java/org/eclipse/ditto/concierge/service/common/ConciergeConfig.java

@@ -45,11 +45,4 @@ public interface ConciergeConfig extends ServiceSpecificConfig, WithHealthCheckC
      */
     ThingsAggregatorConfig getThingsAggregatorConfig();
 
-    /**
-     * Returns the config for persistence cleanup actions.
-     *
-     * @return the config.
-     */
-    PersistenceCleanupConfig getPersistenceCleanupConfig();
-
 }