fix: use port name when port number is not provided in combined routes

[pmalek]

What this PR does / why we need it:

Part of #3296

When user provides only service port name and not the number e.g.

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    konghq.com/strip-path: "true"
    kubernetes.io/ingress.class: kong
  name: nginx-ingress
spec:
  rules:
  - http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: nginx
            port:
              name: http

and CombinedRoutes feature flag is used the translation logic incorrectly used port number which wasn't specified. This PR fixes it.

Which issue this PR fixes:

Special notes for your reviewer:

PR Readiness Checklist:

Complete these before marking the PR as ready to review:

• the CHANGELOG.md release notes have been updated to reflect any significant (and particularly user-facing) changes introduced by this PR

[codecov]

Codecov Report

Base: 74.0% // Head: 74.0% // Increases project coverage by +0.0% 🎉

Coverage data is based on head (2eba44a) compared to base (fd4b1f6).
Patch coverage: 100.0% of modified lines in pull request are covered.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #3313   +/-   ##
=====================================
  Coverage   74.0%   74.0%           
=====================================
  Files        111     111           
  Lines      13290   13285    -5     
=====================================
- Hits        9841    9839    -2     
+ Misses      2820    2818    -2     
+ Partials     629     628    -1     

Impacted Files	Coverage Δ
internal/dataplane/parser/translate_ingress.go	92.3% <100.0%> (+0.1%)	⬆️
internal/dataplane/parser/translate_knative.go	88.5% <100.0%> (ø)
internal/dataplane/parser/translators/ingress.go	92.2% <100.0%> (-0.3%)	⬇️
internal/dataplane/parser/translators/portdef.go	76.9% <100.0%> (ø)
...nternal/controllers/gateway/udproute_controller.go	73.6% <0.0%> (-2.8%)	⬇️
internal/dataplane/kongstate/service.go	66.0% <0.0%> (-1.3%)	⬇️
internal/dataplane/parser/parser.go	90.7% <0.0%> (+1.0%)	⬆️
...nternal/controllers/gateway/tcproute_controller.go	75.6% <0.0%> (+2.6%)	⬆️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[rainest]

Per conversation earlier, while consistently using a number for the port component of the name would be nice, we don't readily have access to it here, as we only have the Ingress available in ingressRulesFromIngressV1(), not the Service. Absent ready access to the resolved port, it's probably not worth going and getting it just for cosmetic reasons, so this will go ahead and use the name.