Service test for dubbo2.6 & fix #305

[qq925716471]

fix #305
服务测试支持dubbo2.6
修改服务测试查询实现方式减少后台请求
修改泛化调用bug

[nzomkxia]

@qq925716471 Service test for dubbo 2.6 is impossible, since Dubbo 2.6 do not have metadata info

[codecov-io]

Codecov Report

Merging #308 into develop will decrease coverage by 0.25%.
The diff coverage is 3.22%.

@@              Coverage Diff              @@
##             develop     #308      +/-   ##
=============================================
- Coverage      19.57%   19.31%   -0.26%     
  Complexity       289      289              
=============================================
  Files             95       95              
  Lines           3582     3603      +21     
  Branches         553      558       +5     
=============================================
- Hits             701      696       -5     
- Misses          2806     2832      +26     
  Partials          75       75

Impacted Files	Coverage Δ	Complexity Δ
...e/dubbo/admin/service/impl/GenericServiceImpl.java	5.88% <3.22%> (-47.97%)	2 <1> (ø)

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[nzomkxia]

Hi @qq925716471 the pr #306 has been accepted to fix #305, can you remove this part in your pr？

[qq925716471]

#311