glooctl get proxy: remove --proxy-ns and --all flags

[jenshu]

Description

Remove the --proxy-ns and --all flags that were added in #9226

Previously, Proxies generated by the k8s gateway integration were saved in the same namespace as the Gateway and we didn't have a way to retrieve them with glooctl get proxy as it was only checking in the gloo install namespace. As the Proxies are now written to the writeNamespace (discoveryNamespace), we can derive the namespace from Settings instead of having the user pass it in via --proxy-ns.

The --all flag was useful when proxies could be generated in different namespaces, but now that they are all written to the writeNamespace, we can simplify the CLI by removing that flag.

Other changes: print proxy namespace and created by in the results table for glooctl get proxy

Testing steps

Manually verified that glooctl get proxy can get the proxies in the write namespace, without the proxy-ns flag. (Note: upcoming PRs will add e2e tests and fix the --edge / --kube filtering for glooctl get proxy)

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works

[solo-changelog-bot]

Issues linked to changelog:
https://github.com/solo-io/solo-projects/issues/6088

[github-actions]

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