Allow disable apollo client cache

[hezhangjian]

Which issue(s) this PR fixes:

Fixes #4181

Brief changelog

• add config apollo.property.file.cache.enable
• if apollo.property.file.cache.enable is false, use RemoteConfigRepository
• add corresponding unit tests

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• Update the CHANGES log.

[codecov-commenter]

Codecov Report

Merging #4199 (50bc5b8) into master (7fb6b8b) will increase coverage by 0.03%.
The diff coverage is 88.88%.

@@             Coverage Diff              @@
##             master    #4199      +/-   ##
============================================
+ Coverage     52.59%   52.62%   +0.03%     
- Complexity     2620     2627       +7     
============================================
  Files           484      484              
  Lines         15192    15200       +8     
  Branches       1571     1571              
============================================
+ Hits           7990     7999       +9     
- Misses         6645     6646       +1     
+ Partials        557      555       -2     

Impacted Files	Coverage Δ
...ramework/apollo/core/ApolloClientSystemConsts.java	0.00% <ø> (ø)
...va/com/ctrip/framework/apollo/util/ConfigUtil.java	82.16% <84.61%> (+0.49%)	⬆️
...rip/framework/apollo/spi/DefaultConfigFactory.java	90.69% <100.00%> (+0.69%)	⬆️
...nfigservice/service/AccessKeyServiceWithCache.java	82.65% <0.00%> (-2.05%)	⬇️
.../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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[hezhangjian]

@nobodyiam After this change, the default value is seted in

  private void initPropertyNamesCacheEnabled() {
    propertyNamesCacheEnabled = getPropertyBoolean(ApolloClientSystemConsts.APOLLO_PROPERTY_NAMES_CACHE_ENABLE,
            ApolloClientSystemConsts.APOLLO_PROPERTY_NAMES_CACHE_ENABLE_ENVIRONMENT_VARIABLES,
            "false");
  }

If we keep the original, it might be confused for there are more than one code setting the init value.

[hezhangjian]

@nobodyiam PTAL again, thanks

[nobodyiam]

lgtm

[nobodyiam]

LGTM