Kickstart UI: remove AWS option for new VPC creation

[miclettej]

Due to CAPA bump, new VPC creation is no longer supported in the CLI. This PR removes the option to create a new VPC from the UI as well.

User is no longer presented with an option to choose between use existing/new; instead they are only presented with form controls for using an existing VPC.

What this PR does / why we need it

Which issue(s) this PR fixes

Fixes #

Describe testing done for PR

Release note

When creating a management cluster on AWS through the Installer Interface (kickstart UI), new VPC creation is no longer supported. User must follow steps to select an existing VPC. This is a result of a CAPA bump that inhibits new VPC creation by the CLI and therefore also the UI.

Additional information

Special notes for your reviewer

[github-actions]

Cluster Generation A/B Results:
https://storage.googleapis.com/tkg-clustergen/4224/20230103194603/clustergen.diff.txt
Author/reviewers:
Please review to verify that the effects on the generated cluster configurations are exactly what the PR intended, and give a thumbs-up if so.

[github-actions]

Cluster Generation A/B Results:
https://storage.googleapis.com/tkg-clustergen/4224/20230103200949/clustergen.diff.txt
Author/reviewers:
Please review to verify that the effects on the generated cluster configurations are exactly what the PR intended, and give a thumbs-up if so.

[github-actions]

Cluster Generation A/B Results:
https://storage.googleapis.com/tkg-clustergen/4224/20230103203219/clustergen.diff.txt
Author/reviewers:
Please review to verify that the effects on the generated cluster configurations are exactly what the PR intended, and give a thumbs-up if so.

[codecov]

Codecov Report

Merging #4224 (38518ca) into main (6652c70) will decrease coverage by 0.88%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #4224      +/-   ##
==========================================
- Coverage   49.31%   48.43%   -0.89%     
==========================================
  Files         451      481      +30     
  Lines       44602    46724    +2122     
==========================================
+ Hits        21996    22631     +635     
- Misses      20530    21967    +1437     
- Partials     2076     2126      +50     

Impacted Files	Coverage Δ
...oller-manager/controllers/v3_cascade_controller.go	66.66% <0.00%> (-10.00%)	⬇️
packageclients/pkg/packageclient/package_update.go	83.57% <0.00%> (-1.43%)	⬇️
cmd/cli/plugin/cluster/available_upgrade.go	16.32% <0.00%> (ø)
.../isolated-cluster/imgpkginterface/client_imgpkg.go	0.00% <0.00%> (ø)
cmd/cli/plugin/cluster/scale.go	17.85% <0.00%> (ø)
cmd/cli/plugin/cluster/machinehealthcheck.go	100.00% <0.00%> (ø)
cmd/cli/plugin/cluster/set_node_pool.go	14.63% <0.00%> (ø)
...olated-cluster/imagepushop/publishimagesfromtar.go	73.17% <0.00%> (ø)
...li/plugin/isolated-cluster/imgpkginterface/util.go	50.00% <0.00%> (ø)
cmd/cli/plugin/cluster/delete.go	12.50% <0.00%> (ø)
... and 24 more

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