[improvement][breaking] Update templates to comply with CAPI v1.11.X

[AshleyDumaine]

(Recreated from #874 which got automatically closed)

What this PR does / why we need it: We need to update the templates since as-is a good number of resources are throwing API deprecation warnings. This will also help to minimize conversions as mentioned in the CAPI upgrade docs:

Note: it is technically possible for providers to keep using v1beta1 types from CAPI v1.11, but this is not recommended because it will lead to additional conversion calls.

This PR also:

• cleans up the cilium-bgp-lb flavor
• temporarily disables k3s/rke2 e2e tests and removes the k3s/rke2 flavors from the MDBook summary until both providers support CAPI v1.11.X.

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: You can read about the API changes here: https://cluster-api.sigs.k8s.io/developer/providers/migrations/v1.10-to-v1.11

TODOs:

• squashed commits
• includes documentation
• adds unit tests
• adds or updates e2e tests

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.97%. Comparing base (c8c68d4) to head (9888963).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #881   +/-   ##
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  Coverage   65.97%   65.97%           
=======================================
  Files          71       71           
  Lines        7959     7959           
=======================================
  Hits         5251     5251           
  Misses       2406     2406           
  Partials      302      302           

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