remove redundant volatile on initialized

[sunshujie1990]

What is the purpose of the change

init(org.apache.dubbo.config.ReferenceConfig#init) is a synchronized method, and field initialized only access in init, so volatile on initialized is redundant.

Brief changelog

remove redundant volatile flag on initialized

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.
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• If this contribution is large, please follow the Software Donation Guide.

[codecov-commenter]

Codecov Report

Merging #9926 (0c9bab5) into master (3a8e5e6) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #9926      +/-   ##
============================================
- Coverage     60.92%   60.88%   -0.04%     
+ Complexity      449      448       -1     
============================================
  Files          1100     1100              
  Lines         44557    44557              
  Branches       6486     6486              
============================================
- Hits          27145    27128      -17     
- Misses        14446    14464      +18     
+ Partials       2966     2965       -1     

Impacted Files	Coverage Δ
.../java/org/apache/dubbo/config/ReferenceConfig.java	70.44% <ø> (ø)
...ntext/event/AwaitingNonWebApplicationListener.java	48.48% <0.00%> (-24.25%)	⬇️
.../apache/dubbo/remoting/transport/AbstractPeer.java	58.69% <0.00%> (-8.70%)	⬇️
...ng/transport/dispatcher/all/AllChannelHandler.java	82.75% <0.00%> (-6.90%)	⬇️
...ng/exchange/support/header/HeartbeatTimerTask.java	68.42% <0.00%> (-5.27%)	⬇️
...he/dubbo/remoting/transport/netty/NettyServer.java	70.17% <0.00%> (-3.51%)	⬇️
...apache/dubbo/common/config/ConfigurationUtils.java	67.74% <0.00%> (-3.23%)	⬇️
...rg/apache/dubbo/common/timer/HashedWheelTimer.java	79.72% <0.00%> (+0.34%)	⬆️
...g/apache/dubbo/registry/consul/ConsulRegistry.java	60.58% <0.00%> (+0.58%)	⬆️
...ache/dubbo/config/utils/ConfigValidationUtils.java	74.00% <0.00%> (+0.66%)	⬆️
... and 3 more

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