Ftr: Add integrate test

[sxllwx]

What this PR does:

The previous PR #520
had some scenarios that were not considered, which led to errors in integration testing when the PR was merged into the local branch.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[codecov-commenter]

Codecov Report

Merging #534 into develop will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop     #534      +/-   ##
===========================================
- Coverage    66.37%   66.36%   -0.02%     
===========================================
  Files          184      184              
  Lines         9723     9723              
===========================================
- Hits          6454     6453       -1     
- Misses        2627     2631       +4     
+ Partials       642      639       -3     

Impacted Files	Coverage Δ
cluster/cluster_impl/base_cluster_invoker.go	62.31% <0.00%> (-10.15%)	⬇️
remoting/kubernetes/client.go	59.01% <0.00%> (+0.65%)	⬆️
remoting/kubernetes/listener.go	57.00% <0.00%> (+0.93%)	⬆️
remoting/kubernetes/watch.go	80.18% <0.00%> (+0.94%)	⬆️
protocol/dubbo/client.go	69.09% <0.00%> (+1.21%)	⬆️

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