Fix the npe issue for old version of gray release rules

[nobodyiam]

What's the purpose of this PR

Fix the npe issue for old version of gray release rules, e.g. [{"clientAppId":"appidA","clientIpList":["127.0.0.1"]}].

Which issue(s) this PR fixes:

Fixes #4380

Brief changelog

• add default constructor for GrayReleaseRuleItemDTO so that clientIpList and clientLabelList will be initialized to empty set.

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• Update the CHANGES log.

[codecov-commenter]

Codecov Report

Merging #4382 (9a282d3) into master (f929541) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##             master    #4382      +/-   ##
============================================
- Coverage     53.19%   53.19%   -0.01%     
  Complexity     2674     2674              
============================================
  Files           489      489              
  Lines         15275    15277       +2     
  Branches       1580     1580              
============================================
+ Hits           8125     8126       +1     
- Misses         6595     6600       +5     
+ Partials        555      551       -4     

Impacted Files	Coverage Δ
...work/apollo/common/dto/GrayReleaseRuleItemDTO.java	0.00% <0.00%> (ø)
...framework/apollo/openapi/entity/ConsumerAudit.java	42.42% <0.00%> (-6.07%)	⬇️
.../framework/apollo/spring/property/SpringValue.java	89.47% <0.00%> (+1.75%)	⬆️
...rk/apollo/spring/property/SpringValueRegistry.java	89.18% <0.00%> (+5.40%)	⬆️

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