Remove deprecated kubernetes.io/ingress.class from examples and tests

[lucacome]

Replaces kubernetes.io/ingress.class with ingressClassName.

Opening it as a draft as I'm not sure if we need to add something to the examples to call out the need to deploy the ingressClass. It's already called out in the https://docs.nginx.com/nginx-ingress-controller/installation/installation-with-manifests/ and we deploy it automatically with helm

[codecov-commenter]

Codecov Report

Merging #3029 (9163d00) into main (d78f57b) will increase coverage by 0.01%. The diff coverage is n/a.

:exclamation: Current head 9163d00 differs from pull request most recent head e5f4dbb. Consider uploading reports for the commit e5f4dbb to get more accurate results

@@            Coverage Diff             @@
##             main    #3029      +/-   ##
==========================================
+ Coverage   52.29%   52.31%   +0.01%     
==========================================
  Files          58       58              
  Lines       16006    15995      -11     
==========================================
- Hits         8371     8368       -3     
+ Misses       7356     7350       -6     
+ Partials      279      277       -2     

Impacted Files	Coverage Δ
...ternal/k8s/appprotect/app_protect_configuration.go	86.16% <0.00%> (-0.58%)	:arrow_down:
internal/configs/configmaps.go	20.21% <0.00%> (-0.17%)	:arrow_down:
internal/configs/transportserver.go	93.78% <0.00%> (-0.04%)	:arrow_down:
internal/configs/virtualserver.go	95.22% <0.00%> (-0.01%)	:arrow_down:
cmd/nginx-ingress/main.go	0.00% <0.00%> (ø)
cmd/nginx-ingress/flags.go	34.42% <0.00%> (ø)
internal/configs/config_params.go	76.74% <0.00%> (ø)
internal/configs/version2/http.go	0.00% <0.00%> (ø)
internal/configs/version1/config.go	0.00% <0.00%> (ø)
internal/k8s/controller.go	11.11% <0.00%> (+0.01%)	:arrow_up:
... and 1 more

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[vepatel]

@lucacome can we do it for docs only first? some tests are breaking because of this change.

[tomasohaodha]

Hi Luca are you going to remove the non-relevant files (as discussed last week)?