Remove embedded-capi feature

[anmazzotti]

What this PR does / why we need it:

This PR removes the embedded-capi feature, since it's now managed by the pre-install job and it is recommended to let the Turtles chart manage this setting.

The test suites have also been removed.

Also note that this will have the side effect of always creating the following resource:

apiVersion: management.cattle.io/v3
kind: Feature
metadata:
  name: embedded-cluster-api
  annotations:
    "helm.sh/hook": pre-install
    "helm.sh/hook-weight": "1"
spec:
  value: false

Rancher does not seem to create it by default (as other Features are).
The Turtles chart will create it or override any existing, which is the desired behavior, however the chart will not clean this up.

The documentation already covers this: https://turtles.docs.rancher.com/turtles/v0.15/en/getting-started/uninstall_turtles.html

Test run: https://github.com/rancher/turtles/actions/runs/12903793122

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

Checklist:

• squashed commits into logical changes
• includes documentation
• adds unit tests
• adds or updates e2e tests

[alexander-demicev]

we should add an e2e test for rancherInstalled=false

related issue #1025

[furkatgofurov7]

@anmazzotti does https://turtles.docs.rancher.com/turtles/v0.15/en/tasks/maintenance/early_adopter_upgrade.html#_re_enable_embedded_capi also need an update?

[anmazzotti]

@furkatgofurov7 No that is good as it is and still required.
The chart does not take care of cleaning up the added Feature, so this is still a manual step the user has to take.

It can be improved by the helm chart by not overriding an already false value, and by deleting the Feature post uninstall, if it was part of the same helm release.