fix subscription when enable monitor

[jasonjoo2010]

What is the purpose of the change

same fix on monitor in 2.7.x

because there is bug which willl block shutdown progress in 2.5.x and it was fixed in 2.6.3.

related: #2110

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[codecov-io]

Codecov Report

Merging #2167 into master will increase coverage by 0.36%.
The diff coverage is 57.14%.

@@             Coverage Diff              @@
##             master    #2167      +/-   ##
============================================
+ Coverage     54.26%   54.63%   +0.36%     
- Complexity     5103     5129      +26     
============================================
  Files           559      559              
  Lines         24947    25187     +240     
  Branches       4447     4568     +121     
============================================
+ Hits          13538    13760     +222     
- Misses         9373     9385      +12     
- Partials       2036     2042       +6

Impacted Files	Coverage Δ	Complexity Δ
...g/apache/dubbo/config/AbstractInterfaceConfig.java	80.78% <57.14%> (-0.75%)	81 <0> (ø)
...ubbo/rpc/protocol/dubbo/ChannelWrappedInvoker.java	41.66% <0%> (-8.34%)	3% <0%> (ø)
...onfig/spring/extension/SpringExtensionFactory.java	78.57% <0%> (-7.15%)	10% <0%> (ø)
...he/dubbo/remoting/transport/netty/NettyServer.java	67.85% <0%> (-3.58%)	8% <0%> (-1%)
...e/src/main/java/com/alibaba/dubbo/rpc/Invoker.java	33.33% <0%> (-3.04%)	0% <0%> (ø)
...dubbo/rpc/protocol/dubbo/CallbackServiceCodec.java	77.2% <0%> (-1.48%)	29% <0%> (ø)
.../dubbo/remoting/transport/netty4/NettyChannel.java	65% <0%> (-1.25%)	22% <0%> (-1%)
.../src/main/java/org/apache/dubbo/rpc/RpcStatus.java	57.89% <0%> (-1.06%)	18% <0%> (ø)
...apache/dubbo/rpc/protocol/dubbo/DubboProtocol.java	58.33% <0%> (-0.84%)	30% <0%> (-1%)
...rpc/protocol/dubbo/telnet/InvokeTelnetHandler.java	55.69% <0%> (+3.79%)	13% <0%> (+2%)	⬆️
... and 4 more

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