support only show difference keys when compare namespace

[lepdou]

What's the purpose of this PR

support only show difference keys when compare namespace

Which issue(s) this PR fixes:

Fixes #4133

Brief changelog

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[codecov-commenter]

Codecov Report

Merging #4165 (57fb2bc) into master (aea31ec) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #4165      +/-   ##
============================================
- Coverage     52.59%   52.56%   -0.04%     
+ Complexity     2614     2613       -1     
============================================
  Files           484      484              
  Lines         15190    15190              
  Branches       1572     1572              
============================================
- Hits           7989     7984       -5     
- Misses         6643     6648       +5     
  Partials        558      558              

Impacted Files	Coverage Δ
...o/openapi/filter/ConsumerAuthenticationFilter.java	94.11% <0.00%> (-5.89%)	⬇️
...ework/apollo/internals/RemoteConfigRepository.java	85.27% <0.00%> (-3.07%)	⬇️
...ervice/service/ReleaseMessageServiceWithCache.java	85.88% <0.00%> (+1.17%)	⬆️

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[nobodyiam]

LGTM