### Environment

* Dubbo version: 3.0
StaticDirectory.destroy方法最后要对列表做clear操作，但是ReferenceConfig的createInvokerForLocal构造StaticDirectory传入的列表类型是Collections.singletonList，执行clear就会抛异常：
```
[08/10/21 07:35:39:302 UTC] main  WARN config.ReferenceConfig:  [DUBBO] Unexpected error occurred when destroy invoker of ReferenceConfig(null)., dubbo version: 3.0.4-SNAPSHOT, current host: 172.19.112.1
java.lang.UnsupportedOperationException
	at java.util.AbstractList.remove(AbstractList.java:161)
	at java.util.AbstractList$Itr.remove(AbstractList.java:374)
	at java.util.AbstractList.removeRange(AbstractList.java:571)
	at java.util.AbstractList.clear(AbstractList.java:234)
	at org.apache.dubbo.rpc.cluster.directory.StaticDirectory.destroy(StaticDirectory.java:91)
	at org.apache.dubbo.rpc.cluster.support.AbstractClusterInvoker.destroy(AbstractClusterInvoker.java:113)
	at org.apache.dubbo.rpc.cluster.support.wrapper.MockClusterInvoker.destroy(MockClusterInvoker.java:79)
	at org.apache.dubbo.config.ReferenceConfig.destroy(ReferenceConfig.java:219)
```
private transient volatile boolean destroyed;
    /**
     * The service names that the Dubbo interface subscribed.
     *
     * @since 2.7.8
     */
    private String services;
    public ReferenceConfig() {
        super();
    }
    public ReferenceConfig(Reference reference) {
        super(reference);
    }
    @Override
    protected void postProcessAfterScopeModelChanged(ScopeModel oldScopeModel, ScopeModel newScopeModel) {
        super.postProcessAfterScopeModelChanged(oldScopeModel, newScopeModel);
        protocolSPI = this.getExtensionLoader(Protocol.class).getAdaptiveExtension();
        proxyFactory = this.getExtensionLoader(ProxyFactory.class).getAdaptiveExtension();
    }
    /**
     * Get a string presenting the service names that the Dubbo interface subscribed.
     * If it is a multiple-values, the content will be a comma-delimited String.
     *
     * @return non-null
     * @see RegistryConstants#SUBSCRIBED_SERVICE_NAMES_KEY
     * @since 2.7.8
     */
    @Deprecated
    @Parameter(key = SUBSCRIBED_SERVICE_NAMES_KEY)
    public String getServices() {