chore(refactor): the translation of upstream

[AlinsRan]

Type of change:

• Bugfix
• New feature provided
• Improve performance
• Backport patches

What this PR does / why we need it:

Backend: The code logic of this part is split into many places, and there is redundancy.

• Decouple the translation of upstream, the logic of this part only exists in one place.
• Delete redundant codes.

Pre-submission checklist:

• Did you explain what problem does this PR solve? Or what new features have been added?
• Have you added corresponding test cases?
• Have you modified the corresponding document?
• Is this PR backward compatible? If it is not backward compatible, please discuss on the mailing list first

[codecov-commenter]

Codecov Report

Merging #1295 (23fe9e6) into master (f71b376) will increase coverage by 0.73%.
The diff coverage is 15.67%.

@@            Coverage Diff             @@
##           master    #1295      +/-   ##
==========================================
+ Coverage   40.62%   41.35%   +0.73%     
==========================================
  Files          75       75              
  Lines        7006     6771     -235     
==========================================
- Hits         2846     2800      -46     
+ Misses       3847     3657     -190     
- Partials      313      314       +1     

Impacted Files	Coverage Δ
...kg/providers/apisix/translation/apisix_upstream.go	100.00% <ø> (ø)
.../providers/gateway/translation/gateway_tlsroute.go	0.00% <0.00%> (ø)
pkg/providers/ingress/translation/translator.go	0.00% <0.00%> (ø)
pkg/providers/translation/translator.go	0.00% <ø> (ø)
pkg/providers/translation/upstream.go	12.42% <14.70%> (ø)
pkg/providers/apisix/translation/apisix_route.go	19.35% <20.83%> (+0.21%)	⬆️
pkg/providers/translation/apisix_upstream.go	80.84% <57.14%> (-0.05%)	⬇️
pkg/providers/apisix/translation/apisix_plugin.go	57.18% <100.00%> (-0.36%)	⬇️
...providers/gateway/translation/gateway_httproute.go	64.10% <100.00%> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[tao12345666333]

could you please resolve conflicts? thanks

[tao12345666333]

Sorry for delay.
There are too many conflicts now. If you want to proceed, you need to resolve the conflict first. thanks

[tao12345666333]

Since there are tons of conflicts and no updates yet, I want to put it in v1.7. thanks