问题描述：NacosMetadataReport#getServiceAppMapping 方法将监听器存入casListenerMap中，key是使用 DEFAULT_MAPPING_GROUP
作为group构建；但是 NacosMetadataReport#removeServiceAppMappingListener方法中，移除监听器时使用group不是 DEFAULT_MAPPING_GROUP，从而导致无法正常移除监听器

~~~
@Override
    public Set<String> getServiceAppMapping(String serviceKey, MappingListener listener, URL url) {
        String group = DEFAULT_MAPPING_GROUP;

        if (null == casListenerMap.get(buildListenerKey(serviceKey, group))) {
            addCasServiceMappingListener(serviceKey, group, listener);
        }
        String content = getConfig(serviceKey, group);
        return ServiceNameMapping.getAppNames(content);
    }

    @Override
    public void removeServiceAppMappingListener(String serviceKey, MappingListener listener) {
        MappingDataListener mappingDataListener = casListenerMap.get(buildListenerKey(serviceKey, group));
        if (null != mappingDataListener) {
            removeCasServiceMappingListener(serviceKey, group, listener);
        }
    }
~~~
try {
            boolean publishResult = configService.publishConfig(identifier.getUniqueKey(KeyTypeEnum.UNIQUE_KEY), group, value);
            if (!publishResult) {
                throw new RuntimeException("publish nacos metadata failed");
            }
        } catch (Throwable t) {
            logger.error("Failed to put " + identifier + " to nacos " + value + ", cause: " + t.getMessage(), t);
            throw new RuntimeException("Failed to put " + identifier + " to nacos " + value + ", cause: " + t.getMessage(), t);
        }
    }
    private void deleteMetadata(BaseMetadataIdentifier identifier) {
        try {
            boolean publishResult = configService.removeConfig(identifier.getUniqueKey(KeyTypeEnum.UNIQUE_KEY), group);
            if (!publishResult) {
                throw new RuntimeException("remove nacos metadata failed");
            }
        } catch (Throwable t) {
            logger.error("Failed to remove " + identifier + " from nacos , cause: " + t.getMessage(), t);
            throw new RuntimeException("Failed to remove " + identifier + " from nacos , cause: " + t.getMessage(), t);
        }
    }
    private String getConfig(BaseMetadataIdentifier identifier) {
        try {
            return configService.getConfig(identifier.getUniqueKey(KeyTypeEnum.UNIQUE_KEY), group, 3000L);
        } catch (Throwable t) {
            logger.error("Failed to get " + identifier + " from nacos , cause: " + t.getMessage(), t);
            throw new RuntimeException("Failed to get " + identifier + " from nacos , cause: " + t.getMessage(), t);
        }
    }
    public class NacosConfigListener extends AbstractSharedListener {