chore: refactor the structures of kube clients, shared index informer factories

[tokers]

Please answer these questions before submitting a pull request

• Why submit this pull request?

• Bugfix

• New feature provided

• Improve performance

• Backport patches

• Related issues

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Bugfix

• Description

• How to fix?

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New feature or improvement

• Describe the details and related test reports.

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Backport patches

• Why need to backport?

• Source branch

• Related commits and pull requests

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[codecov-commenter]

Codecov Report

Merging #431 (5b9f043) into master (dc43be8) will increase coverage by 0.02%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master     #431      +/-   ##
==========================================
+ Coverage   36.58%   36.61%   +0.02%     
==========================================
  Files          43       43              
  Lines        3799     3796       -3     
==========================================
  Hits         1390     1390              
+ Misses       2230     2227       -3     
  Partials      179      179              

Impacted Files	Coverage Δ
pkg/ingress/apisix_route.go	0.00% <0.00%> (ø)
pkg/ingress/apisix_tls.go	0.00% <0.00%> (ø)
pkg/ingress/apisix_upstream.go	0.00% <0.00%> (ø)
pkg/ingress/controller.go	0.00% <0.00%> (ø)
pkg/ingress/status.go	0.00% <0.00%> (ø)

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[tokers]

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