fix: missing upstream name in gateway-api routes

[lingsamuel]

Type of change:

• Bugfix

What this PR does / why we need it:

Bugfix: should set upstream.Name since TranslateContext use it as the key. Otherwise, the generated upstream will be ignored.

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 #1754 (613ff61) into master (c5b2ae8) will increase coverage by 0.03%.
The diff coverage is 63.63%.

❗ Current head 613ff61 differs from pull request most recent head bed677e. Consider uploading reports for the commit bed677e to get more accurate results

@@            Coverage Diff             @@
##           master    #1754      +/-   ##
==========================================
+ Coverage   41.69%   41.72%   +0.03%     
==========================================
  Files          90       90              
  Lines        7702     7707       +5     
==========================================
+ Hits         3211     3216       +5     
  Misses       4127     4127              
  Partials      364      364              

Impacted Files	Coverage Δ
.../providers/gateway/translation/gateway_tlsroute.go	0.00% <0.00%> (ø)
.../providers/gateway/translation/gateway_udproute.go	0.00% <0.00%> (ø)
...providers/gateway/translation/gateway_httproute.go	49.54% <100.00%> (+1.16%)	⬆️

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