Do not log with warning if no extension found

[lonre]

which introduced by #1837 and fix #2827
eg:

    ApplicationConfig applicationConfig = new ApplicationConfig();
    applicationConfig.setName("demo-app");
    applicationConfig.setLogger("slf4j");

What is the purpose of the change

XXXXX

Brief changelog

XXXXX

Verifying this change

XXXXX

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[codecov-io]

Codecov Report

Merging #4975 into master will decrease coverage by 0.1%.
The diff coverage is 50%.

@@             Coverage Diff              @@
##             master    #4975      +/-   ##
============================================
- Coverage     64.03%   63.93%   -0.11%     
+ Complexity      453      450       -3     
============================================
  Files           769      769              
  Lines         33160    33162       +2     
  Branches       5230     5232       +2     
============================================
- Hits          21233    21201      -32     
- Misses         9511     9534      +23     
- Partials       2416     2427      +11

Impacted Files	Coverage Δ	Complexity Δ
...onfig/spring/extension/SpringExtensionFactory.java	81.39% <50%> (+0.9%)	0 <0> (ø)	⬇️
.../apache/dubbo/qos/protocol/QosProtocolWrapper.java	65.85% <0%> (-17.08%)	0% <0%> (ø)
...ache/dubbo/remoting/transport/AbstractChannel.java	75% <0%> (-12.5%)	0% <0%> (ø)
.../remoting/transport/netty4/NettyServerHandler.java	61.9% <0%> (-9.53%)	0% <0%> (ø)
.../apache/dubbo/remoting/transport/AbstractPeer.java	58.69% <0%> (-8.7%)	0% <0%> (ø)
...apache/dubbo/rpc/protocol/dubbo/FutureAdapter.java	53.84% <0%> (-7.7%)	0% <0%> (ø)
...ng/transport/dispatcher/all/AllChannelHandler.java	51.42% <0%> (-5.72%)	0% <0%> (ø)
.../org/apache/dubbo/remoting/ExecutionException.java	15.78% <0%> (-5.27%)	0% <0%> (ø)
...e/dubbo/remoting/transport/netty/NettyChannel.java	57.64% <0%> (-4.71%)	20% <0%> (-1%)
...he/dubbo/remoting/transport/netty/NettyServer.java	69.64% <0%> (-3.58%)	8% <0%> (-1%)
... and 7 more

---

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[beiwei30]

@lonre This is not an issue. The exception stack trace is print out only because the logging level is set to DEBUG.

[lonre]

@lonre This is not an issue. The exception stack trace is print out only because the logging level is set to DEBUG.

Hi, @beiwei30 chould you please check this

#2827 (comment)