[backport v2.10.0] Fix editing local rke1 and eks clusters

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This is an automated request to port PR #12583 by @mantis-toboggan-md

Original PR body:

Summary

Fixes #12506
Fixes #12339

Occurred changes and/or fixed issues

This PR reverts #12177 as well as much of #9868

Technical notes summary

I reverted most of #9868 and moved a critical component of that fix into a display-only property, so it would not interfere with iframed edit pages (causing #12506 and #12339). I also found a simpler approach to determining whether or not a cluster is imported, which doesn't depend on ember query params: as noted in pre-existing inline documentation, constructing those ember params involves "much indirect mapping" -- in other words, it's difficult to follow.

Areas or cases that should be tested

Verify the provider/distro column of the cluster management list view as well as the edit config view for each of the following:
local clusters:

• rke1
• rke2
• k3s
• built-in kontainer (AKS, EKS, GKE)

downstream clusters:

• rke1 provisioned
• rke2 provisioned
• k3s provisioned
• rke1 imported
• rke2 imported
• k3s imported
• kontainer imported (AKS, EKS, GKE)

Areas which could experience regressions

The provider/distro column of the cluster management list view, as well as any iframed ember cluster edit page, could experience regressions. We also need to be sure we haven't re-introduced:

#6836
#11874

Screenshot/Video

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