[v13] Refresh the teleport-cluster Helm guide

[ptgott]

Backports #25287

• Refresh the teleport-cluster Helm guide

Updated the guide while testing it for v13.

The goals of this change are to:

• Update the guide for v13 (these are very minor changes consisting of editing example outputs)
• Simplify the guide
• Make the guide easier to use

Updating the guide:

• Remove the video, which is two years old.

Simplifying the guide:

• Some Tabs components differ only in mentioning an Enterprise-specific namespace instead of an OSS-specific namespace. By using the same namespace for both editions, we can remove these tabs.
• Add tsh as a prerequisite so we don't need to install it midway through the guide.
• Remove the SSO instructions: The SSO instructions rely on following other guides to complete, so these aren't really appropriate for this step-by-step guide. The only difference the SSO instructions in this guide offer from other guides is is running tctl on the Auth Service pod via kubectl exec. Since this isn't actually necessary, we can remove these instructions.
• Refactor out common instructions in the OSS/Enterprise installation tabs
• Remove the command to get the Proxy Service's load balancer IP, since the get services command already shows this

Make the guide easier to use:

• Add more specific Enterprise installation steps, including showing how to get the license file.
• Make the DNS instructions more specific.
• Add guidance in the Prerequisites for ensuring that your cluster supports Persistent Volumes.
• Add a warning re: system:masters
• Add Var components to code snippets so they are easier to copy/paste.

Stray edits:

• Adjust line widths for easier reviews.
• Recommend the local Kubenetes guide in the first Admonition, rather than the Docker Compose guide, since readers will already be interested in Kubernetes.

• Respond to hugoShaka feedback

• Linter fixes

• Respond to alexfornuto feedback