dubbo-spring-boot-actuator compatible with Spring Boot Actuator 2.6.x

[gitchenjh]

What is the purpose of the change

fix #9394
see alse #9426

Brief changelog

Verifying this change

Checklist

• Make sure there is a GitHub_issue field for the change (usually before you start working on it). Trivial changes like typos do not require a GitHub issue. Your pull request should address just this issue, without pulling in other changes - one PR resolves one issue.
• Each commit in the pull request should have a meaningful subject line and body.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Check if is necessary to patch to Dubbo 3 if you are work on Dubbo 2.7
• Write necessary unit-test to verify your logic correction, more mock a little better when cross module dependency exist. If the new feature or significant change is committed, please remember to add sample in dubbo samples project.
• Add some description to dubbo-website project if you are requesting to add a feature.
• GitHub Actions works fine on your own branch.
• If this contribution is large, please follow the Software Donation Guide.

[codecov-commenter]

Codecov Report

Merging #9437 (33a1411) into master (9cfb1ae) will increase coverage by 0.07%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #9437      +/-   ##
============================================
+ Coverage     60.82%   60.90%   +0.07%     
- Complexity      445      447       +2     
============================================
  Files          1100     1100              
  Lines         44509    44515       +6     
  Branches       6475     6477       +2     
============================================
+ Hits          27073    27110      +37     
+ Misses        14466    14441      -25     
+ Partials       2970     2964       -6     

Impacted Files	Coverage Δ
.../apache/dubbo/rpc/protocol/AsyncToSyncInvoker.java	62.06% <0.00%> (-10.35%)	⬇️
...a/org/apache/dubbo/monitor/dubbo/DubboMonitor.java	86.66% <0.00%> (-1.91%)	⬇️
...ng/zookeeper/curator5/Curator5ZookeeperClient.java	51.97% <0.00%> (-1.13%)	⬇️
.../dubbo/remoting/transport/netty4/NettyChannel.java	65.34% <0.00%> (-1.00%)	⬇️
...n/java/org/apache/dubbo/metadata/MetadataInfo.java	34.94% <0.00%> (-0.38%)	⬇️
...dubbo/remoting/exchange/support/DefaultFuture.java	93.69% <0.00%> (ø)
...apache/dubbo/common/extension/ExtensionLoader.java	81.31% <0.00%> (+0.21%)	⬆️
...ting/zookeeper/curator/CuratorZookeeperClient.java	70.05% <0.00%> (+1.12%)	⬆️
...pache/dubbo/registry/support/AbstractRegistry.java	81.48% <0.00%> (+1.85%)	⬆️
...ubbo/registry/support/AbstractRegistryFactory.java	83.09% <0.00%> (+2.81%)	⬆️
... and 7 more

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[kylixs]

LGTM