Remove remaining pieces of k8s exec specific UI pages

[o-nikolas]

See this conversation for more context: #47322 (comment)

tl;dr: We have had one remaining executor coupling (re AIP-51, see 6a here) with the k8s executor having a UI page which renders the kube config. This coupling has stayed unfixed because we have had two options:

1. Create a mechanism for all executors to vend UI pages. This has remained undone because we only have one example of this requirement so it doesn't seem to warrant the complexity and time it would take to build such a mechanism. Also, the state of UI in Airflow has been under flux in recent times.
2. Drop support for the k8s use case, which would remove the requirement of building 1). But this is a breaking change and we have not found a right time to do it, until now :)

As far as I can tell this page has actually already been removed in the recent PR to deprecate the old UI in Airflow, and the kube config endpoint as not as yet been re-created in the new UI. So this PR simply removes some of the remaining bits and pieces that used to trigger that endpoint to be present.

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[jedcunningham]

🍺

[potiuk]

Nice! seems that it was intermittent failure, restarted the failing job.

[potiuk]

Yep. looks good @o-nikolas

[o-nikolas]

Yep. looks good @o-nikolas

Unfortunately one conflict has popped up 😭 I'll resolve that and merge once the build is green again

[potiuk]

Damn

[potiuk]

Moving fast. breaking things

[eladkal]

I may miss context. the intention is to remove the K8S spec tab from the UI?

[o-nikolas]

Moving fast. breaking things

Haha yeah, it was one of my other PRs that caused the conflict so I can't complain to much 😆

[o-nikolas]

I may miss context. the intention is to remove the K8S spec tab from the UI?

The PR description has all the details/history, but the tl;dr is yes. The /rendered-k8s endpoint is actually already removed. This PR just removes some of the remaining config bits left behind.

[o-nikolas]

Any further thoughts you want to add before we merge @eladkal?