adj: Remove instructions for deploying Rancher server

[Brianalmeida]

Removing "please install Rancher on a separate server" as it is confusing for users

Problem:

Currently, the Intergrating with Rancher section in the documentation is contradicting itself and leaving readers confused.

Solution:

Remove the first sentence and combine with the following one to ensure readers are not confused when trying to intergrate Rancher with Harvester.

Related Issue(s):

Related issue: harvester/harvester#9969

Test plan:

Additional documentation or context

[github-actions]

Name	Link
🔨 Latest commit	d360aa4
😎 Deploy Preview	https://697a39117b82d608f9952f55--harvester-preview.netlify.app

[Vicente-Cheng]

Hmm, maybe we need to rephrase this section?
Indeed, we suggest installing the Rancher on the external (the vcluster is a special case).
If we remove this section, users might think, yes, we can install the external Rancher within the Harvester cluster.
But this is not the best practice we recommend.

cc @harvester/tpm, @ibrokethecloud, @ihcsim

[ihcsim]

@Vicente-Cheng I'm under the same impression that external Rancher is the recommended best practice. Either we leave the doc unchanged, and/or mention that vcluster is available as an experimental option, or simply combine line 34 and line 36 and let user decide what works best for them:

"To use Rancher with Harvester, please follow the Deploying Rancher Server document to deploy and provision Rancher and a Kubernetes cluster with the provider of your choice."

[Brianalmeida]

I would shy away from mentioning vcluster as the background leading up to this PR stems from a customer trying to leverage this feature and it not working as efficient as they were expecting. (In my testing, this is more on upstream vcluster then it is on Harvester)